I have been running a 64 bit version of Windows on my development machines at work for a few years now. Overall I have had little problems, but I don't do anything overly taxing - I run development programs. At home I do:
- Video and photo editing
- DVD "backups" (my kids are no longer allowed to touch an original DVD movie)
- Web site tinkering (which includes FTP)
- Virtual PC (for sandboxing apps I want to play with)
- Blogging (obviously)
- and the usual web, email, music etc
For a long time you couldn't find many programs compiled and optimized around 64 bit systems. For the last few years many have been buying 64 bit capable computers, yet running just 32 bit versions of all their software because there wasn't much choice. I myself refused to jump on the 64 bit bandwagon at home simply because compatibility with the things I do was scarce. More than one of my key programs installs a service driver of some sort, and without a 64 bit version, it simply will not run on a 64 bit version of Windows. Standard 32 bit applications that do not have driver dependencies will often work just fine on 64 bit Windows.
Well I am pleased to say that I am now running a 64 bit version of Windows on this machine (feel free to guess, but it's not Vista) and almost all of my key apps are now 64 bit native. Once Sony Vegas Pro 8 (my main video editor) released a free update to a 64 bit version, I decided it was time to jump ship. So I rebuilt my system and so far things have been smooth sailing. And I have been surprised to find 64 bit releases for nearly everything I run now.
Now to be clear, running something 64 bit natively doesn't mean you go twice as fast. Certainly you can see some big gains, but it's application dependant. Poorly written software may not gain anything, or may even run slower. A big win for Windows is the ability to address large amounts of memory (greater than 4GB) - something most standard 32 bit systems cannot do (without PAE support).
In fact, given the 4GB addressing limitation of 32 bit systems, Windows will only be able to use 3.2 - 3.5GB of the 4GB of ram that may exist in your system. This is because the hardware in your machine also requires addressing space, so depending on hardware needs, you will lose physical memory to make everything work. I therefore do not recommend installing more than 3GB in a system if you plan to run XP or 32 bit Vista.
NOTE: There are many variables that make this all pretty complex. Poorly designed systems or systems with poorly written BIOS code can also have problems with memory reported as available to Windows. Chances are though, a recent 64 bit system will be fine.
Anyway, I think I'll be 64 bit from here on out. It's only been a little over a week, but it would take some pretty big compatibility problems to force a rollback at this point.