Will not boot up

My computer will not boot up. It gets stuck at the BIOS window, where u can hit a key to enter setup. I hit the button for setup, and it says its entering set up, but it dosent do anything, hit the bootup seletion pop up window, says i selected that but still nothing.

I put in 2 sticks of ram both 256 mb one was a pc 2700 and the other pc 3200, and and Geforce 5700 256 mb, but it ran fine for a couple of days and now its freezes up at the bios screen and i have no idea what to do

At first i thought it was since i didnt activate windows, since it made me reactivate windows after i put in my new hardware, but wouldnt that boot up and let me put in my key?

 

XP Activation has nothing to the with the bootup issues.
You mentioned the likely culprit yourself; 2 RAM sticks at different speeds!
Even if that setup may appear to run fine for a while, it still is a big NO-NO regardless!!
Remove one of them to see if the problem continues to happen. If for some reason it does, then swap the RAM sticks and try again.

Note: Needless to say, always power down and remove the power cord from the back of the PSU and then after opening the side panel, touch the PSU with one hand so you do not fry any of the internal components with ESD.

 

I pulled out the Stick and nothing, so I removed the cmos battery to reset the bios and now its working but im not putting te 2700 back in.

but in my dell i ran 3200 and 2700 for 6 monthsand nothing happend

 

BIOS reset was my next suggestion. The mobo in question might support both RAM types but not installed together.

As you said, some systems (mobos) tolerate the RAM speed/type discrepancy much better than others so they appear to be running fine for a while but this type of a setup is not proper nevertheless.