[plt-scheme] What is good PC for PLT?

My first post here.

I'll maybe spend next few years using PLT for some graph processing,
automated theorem proving and similar purposes, and I consider buying new
PCs for home and office these days.

What's the best combination of processor and OS and RAM for PLT?

Intel or AMD x86 or Opteron? Linux or Win? Is there any benefit of double
core for PLT programs? How much RAM is PLT capable of using, 4GB or more
or less? Is some combination known to be significantly faster or more
reliable?

Thanks