Need help figuring out matching CPU/mobo/mem, currently runs unstable.?

I'm trying to put together an upgrade, currently unstable: running fine in Linux but Windows XP is not even installable with Blue Screen. Fanning the CPU running at about 40 celsius. Parts: AMD Athlon 64 X2 3800+ Socket 939 from eBay ECS nForce3 Socket 939 from eBay 256 megs of PC2100 DDR 266 from an... show more I'm trying to put together an upgrade, currently unstable: running fine in Linux but Windows XP is not even installable with Blue Screen. Fanning the CPU running at about 40 celsius.

Parts:
AMD Athlon 64 X2 3800+ Socket 939 from eBay
ECS nForce3 Socket 939 from eBay
256 megs of PC2100 DDR 266 from an older AMD 2000+ machine, hopefully this is only thing wrong I do have half a mind to get DDR 400 probably 1GB in qty.

I experienced unstability before that prevent Windows from installing, coupled with low heat I suspect unstability again. I realized this is quite obsolete spec but hardcore gaming is not my aim and this question is quite advanced so I want some concrete answers or tidbits with reasons to back it up; not some teen's hotshot answer.
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