Mobility Radeon 9600 ain't the best. I have a 9800 and I get about the same FPS as you, then again i have a 2.2ghz processor.

What settings are you playing on? You would probably perform well at 1024x768 w/mostly medium settings or 800x600 w/mostly high settings.

Keep tweaking until you find a setting that delivers the performance you desire. I know tweaking can be boring and tedious but that's ALWAYS the first thing I do with a game. I'll sometimes spend hours just tweaking it to no end to get it to run good on my computer.

Half-Life 2 Tweak Guide
^Try that to tweak HL2 even more.

1024x768 around low
800x600 around med

I have same machine as you except Radeon 9800 Pro and 1 gig of ram. I highly recommend getting a gig of ram, it gets rid of pesky caching problems (stuttering).

I get about 70-80 fps @ high at 800x600.

I'm guessing lowering your Half-Life 2 video settings would speed up performance while running Fraps.

You will probably be able to play about exactly what you said, medium settings. My friend has a similar setup and he's able to enjoy it well at medium/lower settings.