wardman, your problems, come mainly from being Vista, as well as a 64bit OS.
My old laptop could handle it fine. My old laptop was
AMD - 1.8ghz single core
Nvidia GeForce 440 Go
512mb ram
WinXP
With those, I could even Zakum with only slight lag.
Anything around that stats should work. Though, it sounds in your case, it may be hardware related.