Windows 7 - Upgrading to 7000 from previous builds? Also 32bit vs 64bit help?

Well, I had failed at upgrading from 6801 to 6956, but was wondering if anyone had betteer luck upgrading from 6956 to 7000? Seeing as 6956 is currently my primary OS... (still have vista and Ubuntu on my system, but 6956 is pretty much all I use =P) it would be nice if I could just upgrade rather than going for another clean install, backing up files and going through the entire reinstallation and settings convig ordeal.

I also have a question about 32bit vs 64bit software. Is it worth me waiting so I can try 64bit build 7000? Will I have application compatibility issues(will I be able to run 32 bit software fine on it)? I only have 2 GB of ram, so the whole memory limit thing is not a problem. Is 64 bit OS with 64 bit software quicker than their 32bit counterparts. I think I have vague answers to my own questions, as I've done my own research, but its rather unclear so I'd rather get information from more knowledgeable sources

Think of this way it's like choosing a Xbox or a Xbox360, on the Xbox360 you can play all the latest games with better graphics and you can still play the older games as well but you can't play Xbox360 games on an older Xbox.

So basically to sum it up the 64bit system has more capabilities and when more software has been made to take full advantage of it there will be a significant performance increase and you will still be able to use your older 32bit apps as well.

if you have more or equal to 4 gigs go for the 64...

64 is the one that can access and use 4 or more (server 32 can too but its not the point of this subject...)