But no, for the store there is no alternative.
I'm on a lesser machine, have AERO and and it all works fine. I would not call it slow.
I'd ask your machine's maker what's up with your machine.
Is there an alternative program to play m4v files and download stuff from the iTunes store? I am running iTunes 10.5 on Win 7 64 bit with 8 GB of RAM and an i7 quad core processor. I find the iTunes program to be BLOATED, SLOW, and cumbersome. It won't remember my password for the store--I have to enter it EVERY time. It keeps dropping my connection for downloads, and not only that, since I am running the AERO GLASS theme, half the time I can't even SEE the damn iTunes program. In short, it SUCKS!