Is the x64 distribution of Windows 7 slower than the x86 one? -

I was wondering if the x64 distribution will be slower than an x86 one when running 32-bit applications? Is this true like it was for Vista and XP?

No; the 64 bit version of Windows 7 is basically the same speed. However, only the 64 bit version of Windows (XP, Vista, 7) can use more than 4gb of ram. Ram is cheap these days, so if you have a processor that supports x64, I would recommend going that route. There are many more Vista/Windows 7 drivers for x64 than even a year or two ago, so driver support should be a non-issue.