If you expect the same performance as a desktop you must have purchased a very high-end tablet.
What you download depends on what you plan to use the tablet for. I own a very cheap (Archos 28) tablet and have downloaded a couple of games, an MP3 downloader and a program that picks up internet radio stations. This allows me to listen to music while I jog and play hangman when I'm bored. I would have downloaded a word processor - but that's not much use when I'm working with a 2.8 inch screen!
Figure out what your main use of the tablet will be, and work from that.