Sorry if this isn't in the right place...

This evening when I tried to start my computer, it wouldn't.

The last thing I did today was to browse the web and check email. I then left the computer alone and it went into hibernation mode (I have it set to do that after a few hours). When I pressed the power button to start it back up, all I got was a black screen with a blinking cursor. I ctr-alt-del to restart, got the Dell bios screen, then back to the blinking cursor (no XP screen at all).

Software: I haven't installed any programs recently.
I'm running Win XP Home. I keep antivirus defs up to date, run AdAware occasionally. I run a software firewall (Zonealarm) and have a Linksys WRT54G router that has a built-in SPI firewall as well.

Hardware: I installed a new video card about 2 or 3 weeks ago, but I haven't had any problems with it at all. I installed a new hard drive a couple months ago or so and no problems with it either.
Computer's a Dell 8250, 2.4 GHz P4 533 MHz FSB, 768 MB RDRAM, 160 GB Seagate HDD (master), 60 GB Western Digital HDD (slave), Radeon 9800 Pro 128 MB, SB Audigy 2, CDRW drive, DVD-ROM drive. I think that's all the major components.

Any idea what happened? AFAIK, I didn't do anything to it-it just won't boot again since it last hibernated. I haven't had a problem like this before-it hibernates rather often.

It would happen now-I have 2 papers to type this week. At least I have a laptop I can use-I hate typing on it, but it'll work.

Thanks in advance for any help.