I am trying (and struggling!) to set up a triple boot of 32bit XP, 64bit Win7 and 64bit OpenSuSE 11.1. The problem isn't the Gigabyte gear (mobo and graphics) and it isn't the software, its the SCSI hardware I've got which doesn't seem to like modern software or is clashing with the SATA controller(s), but that's another story.
As far as Win7 is concerned, I've only been using RC1 (missed out on the Beta downloads) and have to say I'm reasonably impressed. I have completely ignored Vista as I have too many incompatible applications and didn't fancy trying to make them work under Vista when XP does an excellent job. However, I've now got a beefy spec that is wasted with the 32bit XP I've been using, and knowing that 64bit XP isn't friendly towards 32 bit applications I decided to try 64 bit Win7. I have been very pleasantly surprised. Some of the 32 bit software I have been running that I know will not run under 64 bit XP or Vista runs fine unit 64 bit Win7, including some older software I expected to fall flat on its face. Also, having VirtualXP available means I can run the tiny number of 16 bit applications I still need to use. In case you're wondering, the 'real' XP I mentioned above is there as a backup in case Win7 should go belly up (after all, its still not an official release and may have problems) and it also allows me to run a few apps that don't work in Win7 and need hardware access that VirtualXP cannot give.
On the plus side, 64bit Win7 seems to be a good bit faster than 32bit XP (I first noticed hints of this during my brief experiments running 64bit Win7 inside a Sun VitualBox machine running on 32bit XP), it seems surprisingly stable and, after the intial culture shock of a long standing XP user, is pretty easy to use. On the minus side, hardware support is poor (even for a new OS), the lack of large FAT32 partition support is stupid, and that start menu is going to get pretty unusable once a decent number of applications have been installed. I also think the lack of a decent email client is poor, especially as there are no instructions on where to find one, and the idea that the official Euro release will not have a browser is just plain daft. I know its not Microsoft's fault, but its still stupid. I'm just glad it looks like they've changed their mind and will be offering a selection of browsers during install instead.