If the one installed by default works fine leave it how it is. Try gnome-look.org for themes, that's where I get mine. Not sure about the gDesklets problem... I used gDesktlets once, but it was quite some time ago, you might want to try screenlets instead... or google desktop.
oh i just got the one it installed by default...should i undo that?
Whats a good website for themes?
Also when using gDeskltes, each desklet shows up on the bottom task bar, can i get rid of those?
Great! Should work fine, just make sure you get the driver for your 4850 from the ATI website. Once you get the file (it should be a .run file) just open a terminal (don't worry, there's not much terminal work you have to do... it's just when you're installing drivers and such), and type "cd /home/username (or whatever your username is)/Desktop/" Then type "sudo sh nameofdriverfile.run" A window will pop up and the rest is easy. Have fun!