First the VM and XP mode work great and are easy to setup along with use.
I have some old XP software that just have to have it and some classic that are fun to play with every now and then.
But a few things to point out to some of the above...
This is really for buisnesses and people needing to run older software and not games since it would cost the company alot to upgrade software all the time so microsoft can see Win7 with this and make more money off those ppl that must have XP. Why would you want to stay with XP as your OS? Its old, all you get is DX9 when DX11 is about here(for the gamers), Its a great improvment over Vista and I say its the new XP. I personally havent seen a bad review yet and having run the full version of Ultimate for about a month ive had literally 0 problems with anything. Games run and look great, most of my software works on Win7 but the few that are older i just run on my VM XP.
OK lastly with win7 VM XP it automatically addes your real drives like liked drives so its easy to get to ant HDD on your VM but if you save a file in an older program and nothing on win7 know what to do with it it automatically links it to the program on VM XP and starts the VM and the program. Its relly kool