>http://www.legitreviews.com/article/1023/1/

I've actually been running Windows 7 on my UMPC for months now (I have a Sony UX280P). One of the things I noticed right from the start is that it acutally uses less resources that Windows XP. Here is the experiment I did:
I installed Windows XP Pro on the machine. Now since it's a tablet pc I wanted XP Tablet - so I found a way to get that in there as well. Since I like to watch TV I wanted all the XP Media Center stuff too - so I found a way to shoehorn THAT in there too....and due to the way I did all this I was stil able to connect to a domain. So basicly I made a hyrbrid XP Pro Tablet Media Center version of windows...hehehe (XP Ultimate???). Anyway, despite the small size of my UX 280P I managed to get it all to work.
Next thing I tried was Windows 7 Ultimate. No need to hack up the OS because the tablet stuff and the media stuff is already in there. Now the interesting part is if I open the task manager, 7 is actually using less resources than XP....and over all the performance actually seems better. I actually have tinkered around with this a LOT over the past several months - even installing identical software on both machines (I actually have two of these tiny UX 280P's) - and making a long story short - Windows 7 beats XP every time. At one point I tried all this with Vista (just the Business edition) and it made the machine so darn slow it was pretty much useless.
So I have to agree - Windows 7 maybe LOOK a lot like Vista - but when you get right down to it - looks like Microsoft did something right.