Ok, here are a few things to consider:
If you buy a tablet with Windows 7, PLEASE buy one with an SSD. The added overhead of 'Touch', along with all the other rubbish people install literally cripples the machine. If an SSD drive can rescue an Archos 9 from being the slowest Tablet out there, you get the message.
1024 x 600 is not enough. Neither is 1280x600 or anything x600. The 'best' tablet resolution would be anything above 1024x768, x768 being the important factor. Why? If you increase the display DPI to 125%, which dramatically improves the size of windows and options, on a x600 device a whole load of information hangs off of the screen. Great. Thanks for that.
When you have a x768 device, all boxes are larger than normal, fit on the screen and when you change desktop icons to large, you have a VERY easy to use tablet. 1024 x 768 should be a minimum. Heck, even Dell with it's Duo has set DPI to be 125% so I'm sure the others will eventually catch on.
An Atom N550 will be fast enough to run windows 7 just fine, as LONG as the thing has an SSD drive and a few tweaks here and there, but, no-one should really expect people to 'tweak' devices to make them better (Then again, people learn how to jailbreak easy enough so why not learn how to tweak Win7)
Windows 7 Embedded standard: Look it up! (Not to be confused with WIndows 7 CE)
P.s. I've owned a whole load of tablets over the years and currently own an Asus R2h, HP 2740p, a random China oem tablet and selling a viewsonic Viewpad 10