WoW on ATI Radeon x300/x550 (250 MB)Follow

Hello!
Im running world of warcraft on my 3 GHz, 1024 MB RAM pc with x300/x550 ATI Radeon graphic card. Is that normal that im getting 5fps in Tempest Keep or Magtheridon even in Gruul's Lair. Its practically unplayable. Is there any solution how to solve that to improve fps or maybe some utility programms. i Was searching official wow forums, but coulndt find any info about that. In old days before TBC came out it worked well in Molten core, BWL and other instances. good fps and good gameplay. Now in TBC its unplayable. in Shattra thats the same 5 fps :(

Thank you!