I actually have this same problem witht he same graphics card, the Radeon 6650M (2 Gb vram). Mine is in a Acer 7750G with an I5 processor and 8 Gb ram. My game lags. Thanks for posting this.
I actually added these two lines to the Skyrim ini file. This may help you a bit.
iMinMemoryPageSize=100000 and iMaxMemoryPageSize=5000000
Add iMaxAllocatedMemoryBytes=1800000000
I found this tip on these forums yesterday. It helped me a bit. Before I added these lines the opening movie was stuttering and it was not really playable. Now it just lags a bit but I have it on low settings. This card should be able to play the game on medium according the wiki. Any tips for us?
EDIT: and also how to get the launcher to recognize the gpu rather than the integrated card? I would like to smooth out the playability and have the mouths actually catch up to the speech. Thanks in advance for any help!