if I understand what's on the wiki correctly, it is not possible to use an ATI "Radeon HD 3650" card for mining, right?
Yep. And buying a new one just for mining currently doesn't seem too profitable. See http://bitcoinx.com/profit/
to calculate costs and income.
My ~700MHash/s give me ~0.4BTC/day. This is currently less than 3$ per day. This is roughly the same amount of money my rig consumes in electricity. I am lucky not to pay for this electriciy but I cannot scale up as this "free" electricity is part of a "fair use" deal and I guess I am already stretching the deal a bit.