I wouldn't give up so easily if I were you, try these steps to see what will happen.
Get your hands any type of windows xp home or pro cd.
Put it in, and wait for setup to load up, once it does agree to microlosses terms and it will put you at the screen for any partitions that may show up.
If the C:drive shows up, delete the partiton with the windows xp disc, format the that partition windows xp.
Once it shows you how much free space you have, reboot the pc.
Load a stable clean dvd of windows 7 home,pro, or ultimate.
Once the windows 7 installation loads up you should see your partition ready to go, use that partition hit install and you should have no problems installing windows 7 after that.
If so, I recommend you download
Hiren's Boot CD 10.1 and All Other Versions - HTTP Download