Nothing installs on both my computers?

hi, on christmas day i tried installing a game on my desktop computer which my OS is XP and in the middle of the install it told me that some files are corrupted so i tried downloading the game again and on another part of the install it also said the same thing that the files are corrupted. so i didnt give it a thought about it. then i did a windows update and then the updates told me that the files were also corrupted....so i didnt give it a thought anymore and tried a system restore and still not working. then i went on my laptop which the OS is Vista...i tried downloading a game from a different site thinking the games are corrupted, and come to install the programs and i get the same messages...that my files are corrupted....also my windows updates...corrupted....now what am i doing wrong? i try installing my Guild Wars game from a cd...corrupted on BO

TH computers....does anyone have any idea of whats going on? or anything i can do to fix it?

thanks ahead of time

Nothing installs on both my computers?computers

Sounds like your down;oads have given you a virus. If you don't have an atni virus program - get one soonest.