PC trouble...nothing will install ???

I currently have an Alienware custom PC that I wished I had never bought (I was mislead by their false claims). After two years of having that paperweight, it has never worked for more than a couple of days. I have tried everything and their tech support has taken it back twice and it still came back with major problems.

Recently, I reformatted it and installed the VIA 4in1 (4.36) and Detonator 4 (23.11). When I go to install the SB Live Platinum 5.1 software/divers, the installation program always locks up completely. This also happens with various software Mechwarrior 3, which stops almost immediately upon installation.

Yesterday, I took out every card in the computer, leaving only the video card (no sound, modem, DVD decoder...all PCI). I reformatted again and tried to install Mechwarrior to see if it was one of the PCI cards. Installation stopped at 2% and the computer once again, locked up completely.

I don't know what to do. Both the SB Live Platinum 5.1 software/driver and Mechwarrior 3 game installed fine before. Now after the reformat, they lock up the computer every time I try to install them.

Also, the computer tends to locks up when I am at the desktop, checking the settings. This is with just the VIA drivers and Detonators installed.

Is this a hardware issue? Here are my specs:

CPU - AMD Athlon 800MHz
Mobo - Asus K7V VIA KX133
Graphics - Guillemot 3D Prophet GeForce 256 DDR
Sound - SB Live Platinum 5.1
Modem - 3Com 56K Fax
DVD decoder - realmagic hollywood
HD - 27GB IBM deskstar
DVD-ROM - Pioneer 8x/40x
CD-RW - HP 9100i

Thanks for the suggestions. Here's the info:

1. I don't have a CPU temp monitor that I can access in the BIOS. However, I do have a mobo temp monitor that shows on the average, 27C-29C.
2. I have a 300 watt power supply.
3. I am 99.999% certain that my RAM is not overclocked, since I don't play around with clock settings (not tech smart enough).

When I removed all of the PCI cards, I left the side case panel off. When I tried to install SB Live Plat 5.1 and other software, it still locked up.

Today, I managed to install Microsoft Office (only piece of software that installs completely without problems). However, when I was writing my paper, it kept on locking up. It would lock up less than 5 mins after the reboot. This would go on for about 3 tries and then I could use the computer without it locking up for about 20-30 mins.

This completely baffles me. The first time I did a full reformat (a month ago), I was able to install everything with no problems except for the PC being unable to detect my PCI modem. Things just went downhill from there. Having some software install while others locking up randomly certainly does not help.

I have also suspected bad RAM since removing the PCI cards did nothing. I'll probably be checking each stick to try to isolate the bad stick.

Thanks for the help.

No, I haven't updated the BIOS recently. I have the Asus K7V with the KX133 chipset. I would find the BIOS at Asus' site right? What do I do after I find the proper BIOS update?