I also have HD5650 on HP 3030TX laptop, and haven't seen this mentioned on the forums yet, so that's how it worked for me.
After (or before?) installing the latest driver, first, set "radeon.modeset=0" as per instructions above; once the driver is installed, set "aticonfig --initial", then BEFORE you reboot, look up the set of commands for aticonfig (aticonfig --help): one of the commands towards the end lets you set the card to run in discreet graphics mode (using one GPU instead of both), would be like "aticonfig -p" or something to that effect. Once I've done that it began to work perfectly. Now if I can just get the GPU to be recognized by pyrit, and stop desktop effects from being disabled on every startup, everything will be perfect.