evil evil virus

Whenever I try to start up my computer, instead of going through the normal startup routine, the blue Windows XP screen comes on, and no matter what I try (pressing F8; Cntrl, Alt, Dlt; or puttin in my XP Installation CD, the computer is stuck on that screen.  What to do?  

What happened before this event occured?

the only thing that i can think of was a couple of messages came up saying that a file wasn't working and needed to be reinstalled.  but they were all pretty periferal files like messaging systems and stuff.  this happened the last time i turned the comptuer on.

You should get an installation/restore screen when you enter  the XP CD whilst booting.

Did you set your CD-ROM to 'First Boot Device'?

 I don't get an installation/restore screen.  I guess I didn't reset cd. I didn't know to.  Just get blue logo screen after it loads.

Do you know how to change the boot device?

Do you know how to enter the BIOS?