Vista 64 has been working as well as one would expect Vista 32 to work for me on my systems. i.e. all the "known" VISTA annoyances / bugs are there, but it's no worse in 64 bit than in 32 bit.
The only really annoying thing that's "special" about 64 bit is that they have *mandatory* driver signing (with Microsoft approved signing credentials only) requirements for kernel drivers in Vista 64, but not Vista 32. So if you're developing or using beta test / open source drivers which are not signed/approved, for instance, you may have a problem in Vista 64. Most average end users won't have a problem with this, though it's a PITA for developers and people that feel that *they* should control their own machine's configuration / software choices.
I've been running Vista 64 with a Q6600 / 8GB RAM and before that with an X2-4400 and 3 GB RAM and they've been OK, I've never had too much software incompatibility with Vista 64 that wouldn't ALSO have been the same with Vista 32.
Hmm Vista related software problems I've seen have included Cygwin and its X-windows, an older release of Adobe Acrobat Reader, an older Partition Magic, some older AntiVirus / Firewall versions, some quirks with Visual Studio 2005, some problems with the older SQL server 2005, just things like that. Mainly related to obsolete versions or development tools.
I think having Vista 64 now is beneficial simply because DDR2 RAM is about as cheap as it ever can / will likely be right now, so if you're EVER going to expand to/past 4GB of DDR2, now is a great time to do it. And if you do so, then you'll need Vista 64 if you're not going to run some other 64 bit OS.
I think Vista 64 with >= 4GB RAM helps the performance of ANY system whether you're using it for games or anything else, simply because more of the application / OS data will fit in RAM disk cache and thus reloading / swapping times will be substantially reduced even for applications that don't use more than 1-2GB of program/data memory directly because their access speed to their data files will be better.
Also Vista is probably about as inexpensive as it's ever likely to get soon because they're probably going to be clearing out all the pre-SP1 media versions from retail stock since they'll be obsolete in a few weeks when SP1 gets here. So there have been some Vista deals at substantial discounts from the usual near-MSRP prices because of that. So if you're EVER buying VISTA retail, it's not necessarily a bad time to do that.
Of course if you wait 1.5 months to order the 64 bit disc, you'll probably get a SP1 integrated disc, so in that case it'll be better to wait to get that.
