Re: Horrible FPS on Minecraft
Although I am not familiar with that specific video card, if Additional Drivers does not show you having flgrx "activated and in use", try activating flgrx and see if that helps.
What cpu do you have?
Minecraft is playable with keyboard and wireless mouse on my 1 GHz 2 core 2 GB tablet PC with Radeon HD 6250 graphics in 64-bit 11.10 or 12.04 w/openjdk-6 booted from SD card. Admittedly minecraft 1.4.2 only averages around 10-20 fps, but that is not so noticeable on its small 10" 1280x800 screen that I normally only use when out of town.
There are some video options in minecraft for Fast vs. Fancy graphics, Fast vs. Balanced, reduced particles, etc. While they have been trying to optimize minecraft speed, some things added in 1.4.2 make it potentially slower than 1.3.2 on a slow computer (not noticeable on much faster desktop).
i5 650 3.2 GHz, 8 GB, nvidia GTX 550 Ti 32" 1080p | i7-4700, 8 GB, Intel HD 4600/nvidia GTX 765M 15.6" 1080p | etc.