Many people don't realize that almost all new computers have a 64 bit processor. However, it is possible to run a 32 bit OS on these new processors without any problems. Actually, most computers ship with a 32 bit operating system still.

If you consider yourself technically savvy it is perfectly fine to go with a 64 bit operating system. However, it is highly likely that you will run into some problems with various software packages. Specifically, there have been some problems with OneNote and 64 bit. OneNote is my favorite note taking software, so this has kept me away from upgrading to 64bit.

As for how much RAM, get as much as you can afford. Vista runs quite well on computers with 2GB of RAM. If you want to go for 4GB and 64 bit, you will have a very powerful system.

Another consideration is that hardware devices such as printers, scanners, cameras, and web cams may not have 64 bit drivers available from the manufactures. Be sure to check for drivers before you make any purchases so you don't have devices that you can't use. Microsoft requires that all drivers on a 64 bit OS be signed. This means more work for manufactures and they do not want to pay to make drivers for older hardware. This will become less of a problem as older hardware becomes obsolete and is no longer used.

It really comes down to if you are willing to put up with some problems. The difficulty in making a decision like this is that you won't know if you will run into problems. The good news is that if you run into problems you can simply install Vista 32 bit if you don't want to stick with 64 bit.