Hi everyone, I have to admit that this is the first time I've posted to this kind of forum before but I really need some help of people who know more than me. It's a bit of a long story, so I'll tell it stage by stage. I picked up a bit of a a bargain a few weeks ago- a 2nd hand machine at a pretty low price because there was a password blocking the BIOS- not a problem thought I, how often do I need to tweak the BIOS? So, all was well- installed Windows XP and various applications with no hitches. But, I was getting fed up with the onboard video stealing memory and just not being very good- I opened the box, only to find only 1 free PCI slot to be seen. So, off I went, trawling the used parts shops and I found a rather nice 128MB Geforce 5200 PCI card- sweet! I bought it, took it home, stuck it in and installed the drivers- but no joy. So, after a bit of research I discovered I needed to change the video settings in the BIOS- oh dear, I can't get into the BIOS..... So, after further research I discover that apparently removing the CMOS battery would reset the BIOS, password and all- I try this and yes it does- I can get into the BIOS setup- joy!! For a second, I leave the setup and try to boot the machine and........nothing!! Except a wee message telling me "no operating system found" ****, thought I, I need to reinstall Windows- oh well there's nothing too important I'll lose...... in with the Windows CD and.........nothing. Got an error message- media error- check the cables!! back into the BIOS setup and after playing around with the boot settings, got the windows cd to boot- kind of..... Setup initialises and then quits to "prevent problems with your computer"- the very nasty blue screen tells me to run a hardware diagnostic utility, paying particular attention to "memory check, mismatched/ faulted memory" Other than that, the machine won't do anything!! All I did hardwarewise was to remove PCI ethernet and USB boards to get at the battery- neither of which are currently in the machine. My machine is an NEC Valuestar VF 300/5 (not sure if it's available outside of Japan), Celeron 1.8ghz, 512 MB (32 of which is taken by onboard video). Not too sure of the motherboard but it has an SiS 962L chipset. PLEASE HELP ME SOMEONE!!! Any advice will be extremely gratefully received.