The only thing that really stands out as being 'possibly' problematic is the video card you have.
Drivers are available from ATI (9.4) but are experimental under Windows 7. Otherwise, your system should sing along quite nicely and, yes, even see an improvement over Vista.
You *could* try using the WDDM1.1
drivers from Microsoft. They're not as effecient as the 9.4 Catalysts for my HD4870x2's but they're not 'laggy', either.
It's pretty unanimous the Windows 7 boots considerably faster than Vista. Yours should, too.