Very bad framerate?

Hello.

I have a very bad framerate at BFBC2 and I wonder why, here is my computer specs:
4 GIG Ram
1 TB Harddrive
AMD Phenom(tm) 9550 Quad-Core Processor 2.20GHz
ATI Radeon HD 3600 Series

I believe I should be able to play with a high framerate at the lowest graphics, but it isn't so.

What might be the problem? When I bought the game the man I asked said it should be able to run properly, even in medium graphics, however he said high graphics would lagg at my computer.

Check the requirments.
And Start > Run > dxdiag > Save it and view it and see if it's up to the requirments,
Your graphics card might be outdated hence update your graphics card / driver by going to the ATI Site.