Performance of x86 Guest on x64 Host

[lcm]

Will the performance an x86 Guest on an x64 Host be identical to that of an x64 Guest, all else equal?

In particular, will Vista x64 Guest performance better than XP x86 Guest on a laptop with an Intel Core 2 Duo CPU @ 2 GHz and 4 GB of RAM. Assume that I will dedicate 3 GB of RAM in both cases.

I need to know whether Vista x64 will perform better than XP x86 because I will be running the Windows OS extensively as Guests on an Ubuntu x64 Host, using it for gaming and the internet. I'm using it for gaming because I don't prefer WINE. I'm using it for the internet because Ubuntu doesn't support blackberries.

I think XP x86 will run faster because I don't think the benefit of having an x64 system outweighs the cost of the excessive RAM usage of Vista x64 (I can get XP down to 150 MB, while I can't get Vista below 1 GB idle). Correct me if I'm wrong - and remember, whether I choose to use Vista x64 or XP x86, I will dedicate a maximum of 3GB to the Guest OS, so the RAM limitations of x86 systems are a non-issue here.

[TerryE]

Given that XP-32bit runs faster than Vista-64bit even on bare hardware, then what do you think the answer is ?

As to using a Windows guest for gaming then don't set your expectations too high. The guest only has one core, and the virtualised graphics adapter only routes openGL to the hosts Graphics Card, and not (yet) direct X.