Can't access BIOS, no command promt

[dfontenot81]

Hello,
I have a Dell Dimension 3000, windows xp home (sp2, build 2600), and I'm *pretty* sure I have a Phoenix BIOS. I know HOW to get into BIOS, (F2 at the promt on mine) but I changed something, trying to assign the IRQ to VGA, now it automatically goes to windows, without even gving me the BIOS promt, how do I reverse this? Somebody help me out here, PLEASE??!
Thanks

[edwin]

hit the F2 key from the moment you power it on and eventually you will get through and into the bios.