This is very odd BUT.........
My stuff is torn down at the moment. House cleaning time.
I usually do all my recording with my XP laptop. The other day I wanted to do a quick little bass part so thought I'd use my Win7 x 64 laptop that was hooked up to the mixer at the time. I couldn't seem to get that bass part to play tight to the other tracks. Thought it was me. Might not be now that you bring this up. When I get set back up I'll give it a go. I use a PCMCIA card. Audidgy2ZS notebook with KX drivers. The only difference between the 2 setups is the drivers for the card are different versions.
ESI Gigaport HD+
Lenovo Turion II /4 Gig Ram/ Win7x64
"The only Band is a Real Band"