well, you could build many different solid builds depending on how much you want to spend. also, are you gonna use linux because you don't have another OS or just because of prefrence?
you could use the windows 7 rc, which is free to use until march of next year, then pickup the full version this october. it is much better than both xp and vista, and many people on these forums use it daily with no problems, including me.
Windows 7 Release Candidate
if the budget is not set, then you could with an i7 build that would go for around $900. maybe you could offer a price range.