P4 P5 and P7 wires disconnected

Hello,
My PC no longer works, so I asked for help. (http://www.commentcamarche.net/forum/affich 12523979 opening the PC startup problem) I was advised to check if the hard drive was not functioning. I did this by booting from Ubuntu. But when I launch it on the PC, it loads for a few seconds and then freezes.

So I deduce that it may not be the hard drive that is causing my problem?

It could be my other issue mentioned in my first message: my unplugged wires. These are the P4, P6, and P7 wires. I took photos to show you.

http://img194.imageshack.us/img194/8726/dsc02805j.th.jpg
http://img40.imageshack.us/img40/3890/dsc02806.th.jpg
http://img29.imageshack.us/img29/4533/dsc02807z.th.jpg

So do you know where these three wires are supposed to connect?

Or is it really the hard drive that is causing my problems? In that case, why can't I launch Ubuntu?

Thank you for your replies.

Configuration: Windows Vista Firefox 3.0.10 PC: DELL Inspiron 531 motherboard: ASUS M2N61-AX