Ordinateur devenu lent

Bonjour,
Mon ordinateur est,devenu lent et je me demande si je n'ai pas un ou plusieurs virus responsables.

J'ai utilisé CCleaner, ad aware, spybot et avast antivirus cleaner. Spybot a trouvé un trojan qu'il a supprimé. l'ordinateur tourne un peu mieux mais pas encore comme avant...
Pourriez-vous m'aider svp. J'ai fait un rapport hijackthis.

Logfile of Trend Micro HijackThis v2.0.2
Scan saved at 00:18:49, on 06/09/2008
Platform: Windows XP SP2 (WinNT 5.01.2600)
MSIE: Internet Explorer v6.00 SP2 (6.00.2900.2180)
Boot mode: Normal

Running processes:
C:\WINDOWS\System32\smss.exe
C:\WINDOWS\system32\winlogon.exe
C:\WINDOWS\system32\services.exe
C:\WINDOWS\system32\lsass.exe
C:\WINDOWS\system32\svchost.exe
C:\WINDOWS\System32\svchost.exe
C:\Program Files\Alwil Software\Avast4\aswUpdSv.exe
C:\Program Files\Alwil Software\Avast4\ashServ.exe
C:\WINDOWS\system32\spoolsv.exe
C:\Program Files\Fichiers communs\Microsoft Shared\VS7Debug\mdm.exe
C:\Program Files\Dell\NICCONFIGSVC\NICCONFIGSVC.exe
C:\WINDOWS\Explorer.EXE
C:\Program Files\Alwil Software\Avast4\ashMaiSv.exe
C:\Program Files\Alwil Software\Avast4\ashWebSv.exe
C:\WINDOWS\system32\hkcmd.exe
C:\Program Files\Synaptics\SynTP\SynTPLpr.exe
C:\Program Files\Synaptics\SynTP\SynTPEnh.exe
C:\WINDOWS\system32\dla\tfswctrl.exe
C:\PROGRA~1\ALWILS~1\Avast4\ashDisp.exe
C:\WINDOWS\system32\ctfmon.exe
C:\Program Files\Google\GoogleToolbarNotifier\GoogleToolbarNotifier.exe
C:\Program Files\Spybot - Search & Destroy\TeaTimer.exe
C:\WINDOWS\System32\svchost.exe
C:\Program Files\NETGEAR\WG511v2\wlancfg5.exe
C:\Program Files\Trend Micro\HijackThis\HijackThis.exe

R1 - HKCU\Software\Microsoft\Internet Explorer\Main,Default_Page_URL = http://www.euro.dell.com/countries/fr/fra/gen/default.htm
R0 - HKCU\Software\Microsoft\Internet Explorer\Main,Start Page = https://www.free.fr/freebox/index.html
R0 - HKLM\Software\Microsoft\Internet Explorer\Main,Start Page = http://www.euro.dell.com/countries/fr/fra/gen/default.htm
R0 - HKCU\Software\Microsoft\Internet Explorer\Toolbar,LinksFolderName = Liens
O2 - BHO: AcroIEHlprObj Class - {06849E9F-C8D7-4D59-B87D-784B7D6BE0B3} - C:\Program Files\Adobe\Acrobat 6.0\Reader\ActiveX\AcroIEHelper.dll
O2 - BHO: Spybot-S&D IE Protection - {53707962-6F74-2D53-2644-206D7942484F} - C:\PROGRA~1\SPYBOT~1\SDHelper.dll
O2 - BHO: DriveLetterAccess - {5CA3D70E-1895-11CF-8E15-001234567890} - C:\WINDOWS\system32\dla\tfswshx.dll
O2 - BHO: Google Toolbar Helper - {AA58ED58-01DD-4d91-8333-CF10577473F7} - c:\program files\google\googletoolbar1.dll
O2 - BHO: Google Toolbar Notifier BHO - {AF69DE43-7D58-4638-B6FA-CE66B5AD205D} - C:\Program Files\Google\GoogleToolbarNotifier\2.0.301.7164\swg.dll
O3 - Toolbar: (no name) - {BA52B914-B692-46c4-B683-905236F6F655} - (no file)
O3 - Toolbar: &Google - {2318C2B1-4965-11d4-9B18-009027A5CD4F} - c:\program files\google\googletoolbar1.dll
O4 - HKLM\..\Run: [IgfxTray] C:\WINDOWS\system32\igfxtray.exe
O4 - HKLM\..\Run: [HotKeysCmds] C:\WINDOWS\system32\hkcmd.exe
O4 - HKLM\..\Run: [SynTPLpr] C:\Program Files\Synaptics\SynTP\SynTPLpr.exe
O4 - HKLM\..\Run: [SynTPEnh] C:\Program Files\Synaptics\SynTP\SynTPEnh.exe
O4 - HKLM\..\Run: [dla] C:\WINDOWS\system32\dla\tfswctrl.exe
O4 - HKLM\..\Run: [avast!] C:\PROGRA~1\ALWILS~1\Avast4\ashDisp.exe
O4 - HKCU\..\Run: [ctfmon.exe] C:\WINDOWS\system32\ctfmon.exe
O4 - HKCU\..\Run: [swg] C:\Program Files\Google\GoogleToolbarNotifier\GoogleToolbarNotifier.exe
O4 - HKCU\..\Run: [SpybotSD TeaTimer] C:\Program Files\Spybot - Search & Destroy\TeaTimer.exe
O4 - HKUS\S-1-5-19\..\Run: [CTFMON.EXE] C:\WINDOWS\system32\CTFMON.EXE (User 'SERVICE LOCAL')
O4 - HKUS\S-1-5-20\..\Run: [CTFMON.EXE] C:\WINDOWS\system32\CTFMON.EXE (User 'SERVICE RÉSEAU')
O4 - HKUS\S-1-5-18\..\Run: [CTFMON.EXE] C:\WINDOWS\system32\CTFMON.EXE (User 'SYSTEM')
O4 - HKUS\.DEFAULT\..\Run: [CTFMON.EXE] C:\WINDOWS\system32\CTFMON.EXE (User 'Default user')
O4 - Global Startup: NETGEAR WG511v2 Wireless Assistant.lnk = ?
O8 - Extra context menu item: E&xporter vers Microsoft Excel - res://C:\PROGRA~1\MICROS~3\Office10\EXCEL.EXE/3000
O9 - Extra button: (no name) - {08B0E5C0-4FCB-11CF-AAA5-00401C608501} - C:\Program Files\Java\j2re1.4.2_03\bin\npjpi142_03.dll
O9 - Extra 'Tools' menuitem: Console Java (Sun) - {08B0E5C0-4FCB-11CF-AAA5-00401C608501} - C:\Program Files\Java\j2re1.4.2_03\bin\npjpi142_03.dll
O9 - Extra button: (no name) - {CD67F990-D8E9-11d2-98FE-00C0F0318AFE} - (no file)
O9 - Extra button: (no name) - {DFB852A3-47F8-48C4-A200-58CAB36FD2A2} - C:\PROGRA~1\SPYBOT~1\SDHelper.dll
O9 - Extra 'Tools' menuitem: Spybot - Search & Destroy Configuration - {DFB852A3-47F8-48C4-A200-58CAB36FD2A2} - C:\PROGRA~1\SPYBOT~1\SDHelper.dll
O9 - Extra button: Messenger - {FB5F1910-F110-11d2-BB9E-00C04F795683} - C:\Program Files\Messenger\msmsgs.exe
O9 - Extra 'Tools' menuitem: Windows Messenger - {FB5F1910-F110-11d2-BB9E-00C04F795683} - C:\Program Files\Messenger\msmsgs.exe
O23 - Service: avast! iAVS4 Control Service (aswUpdSv) - ALWIL Software - C:\Program Files\Alwil Software\Avast4\aswUpdSv.exe
O23 - Service: avast! Antivirus - ALWIL Software - C:\Program Files\Alwil Software\Avast4\ashServ.exe
O23 - Service: avast! Mail Scanner - ALWIL Software - C:\Program Files\Alwil Software\Avast4\ashMaiSv.exe
O23 - Service: avast! Web Scanner - ALWIL Software - C:\Program Files\Alwil Software\Avast4\ashWebSv.exe
O23 - Service: Google Updater Service (gusvc) - Google - C:\Program Files\Google\Common\Google Updater\GoogleUpdaterService.exe
O23 - Service: Intel NCS NetService (NetSvc) - Intel(R) Corporation - C:\Program Files\Intel\PROSetWired\NCS\Sync\NetSvc.exe
O23 - Service: NICCONFIGSVC - Dell Inc. - C:\Program Files\Dell\NICCONFIGSVC\NICCONFIGSVC.exe