...I just want AE CS5 with 32 bit support....
Sorry, you're out of luck. AE 10 is exclusively a 64-bit application. It doesn't come in a 32-bit version.
...where can I download the CS4 version?
Buy it on EBay?
I must be wrong, but I am sure that I read that if you download the CS5 Master Collection it comes with 32bit support to ease the transition over to 64bit.
I don't want to buy it just yet. I really need to try it first, which is why I want to download it. I currently use Sony Vegas and have been told AE is better by far. As I use Sony Vegas for a lot of things, I need to download it and try it first to see if AE is right for me.
Gotcha. If that's the case, go to prodesigntools-dot-com. Look in the May 2010 archive: you'll find the AE CS4 tryout. I'm pretty sure the 30-day time limit will still apply, and it won't have the third-party plugins that normally came bundled with the regular version. So there will be no Keylight nor the Cycore effects, e.g. CC Mr. Mercury or CC Sphere.