Windows 2000 Pro.

Did you verify that your newly installed hardware was on Microsoft's Hardware Compatability List?

Try uninstalling one of the pieces of hardware and see if it lets you boot up normally.

I am going to assume that the ZIP and CD burner are IDE devices. And that you have a regular CD and Hard drive.

Try this configuration.

Put the Hard drive on the 1st IDE cable as a master drive. Jumper the Burner CD as a slave drive and put iton the same cable.

Put the ZIP drive in as a master drive and put it on the 2nd IDE controller. Last jumper the normal CD to slave and attach it with the same cable as the zip drive.

Try that and see if it works.

If the system still does not boot! Disconnect the CD burner and leave the Hard drive by itself and see it it boots.

If it still does not boot, remove the Zip drive.

Now if it does boot, reconnect the CD Burner.

IF it does boot then the Zip drive interface it bad! Replace the zip drive.

ok if it boots in VGA mode then try adjust your screen settings to something like 800*600 then try a normal boot up. This sounds like your monitor can't handle the screen size in normal mode so give that a go and tell us how you get on. It would also be intresting to know your exact system setup.
Cheers

Another thought is that one of your new toys is presenting a conflict of some sort with your video controller.

The first thing I would do is go into the BIOS setup and check to see if any conflicts are reported there. Also, just make sure the "system" sees everything.

Assuming all of that is OK, just boot up into VGA mode, and poke around with the O/S loaded. Look in the Device Manager for possible conflicts. You may need to move a controller, or adjust some IRQs or whatever.

If your video controller is PCI, you could also try moving it to a different slot (but that's a longshot).