PC keeps locking up

[Madasafish]

I have and old PC which was running Win98SE and the dam thing keeps locking up after about 5-10mins.
It was never down to one thing whether I was looking at files on a CD or just browsing on the Internet the PC would lock up.
I formatted the harddrive and installed win2000 Pro it installed fine but after its first reboot it got to the loading security settings screen and then low and behold it just froze. I rebooted which seemed OK but after a few mins loading some other programs on it froze again, ctrl+alt+del doesn't even work.
Is this a case of a knackered harddrive or something more.
I know the PC had trouble with the dreaded 'Mywebsearch' and other nasty parasites, is it time for a new harddrive?

PC spec - AMD Athlon 1500+, 256Mb RAM, 20Gb harddrive,
PCI modem card although this isn't used as the PC is connected to
NTL Broadband, on-board graphics.

Please can anyone help?

[Thrax]

http://www.memtest.org/
One error means bad memory.

[Tex]

You might also sit in the bios for awhile and watch your temps. make sure the heatsink/fan is functioning and not clogged with dirt.

[Madasafish]

Tried using memtest, but when I click on the install.bat file to create a bootable floppy it doesn't work.
It say's Attempt to DMA across 64K boundary.
Installation failed.
Does anyone know why?

[Thrax]

Try the bootable CD iso.