Stick with 32bit for now.
As said by me and many other people before:
1. The support just isn't there, and won't be for awhile.... Some things will never have 64bit drivers!
2. The performance "boost" is hardly noticeable, and only when you are running 64bit programmes. In which there arn't that many.
3. Not many people have more then 4GB of memory, which is the main reason to go 64bit.
4. 16bit, yes ole faithful, do you have any 16bit programmes you want to use? With 64bit Windows thats a no go!
5. Some programmes (32) dont like 64bit, although this is only a handful.
6. Flash and Java, both dont work on 64.... (JRE and JDK work fine, but as for the browser plugin ...)
7. Thats all i can think of for now.