Howdy CB,
Usually folks that respond here like to see at least some idea for a build to critique/tweak it. Coming to the board with empty hands and no ideas for parts generally gets you nowhere.
That being said, you really should do a little bit of research on your own and come up with some ideas. You've figured out how to make an account/find the right forum/post- you should be able to read some of the other posts here and get an idea.
At $800 you can go any number of roads and build a great system. You could spend $100 to $200 less and still have something very nice that will likely meet your needs for at least the next couple of years.
I'm not going to bother posting a build for you. If you really want to build your own rig you owe it to yourself to educate yourself. Spend a day here on tom's and read and you'll be much more informed and you can put together a good idea of what you want. Come back in a day or two and make a list and post it. You'll have a much greater sense of accomplishment in coming up with your own idea and tweaking it rather than being spoon fed someone else's idea. What if 10 people post 10 different ideas on a rig here for you? How do you pick? Price alone? What if someone uses a piece of crap PSU in the build and you don't know because you haven't read reviews, etc?
This isn't a beat down, if its making you feel that way. I build my first rig a couple months back and came in pretty blind. But I read other builds in this forum, read responses here, read product reviews on newegg and figured out a basic idea of what I wanted before I posted my build here. Some parts I changed after reading responses. Some parts I kept, in disagreement with responses.
There is a pretty nice build a few posts down for an i5 system (read- $700 gaming rig). Read that one. There are TONS of builds in your range.
One last suggestion. AMD's next generation (Bulldozer) is due to be released in about 3 weeks. At this point I would wait for that release to see response. At the very least AMD's other products may see price drops. Even better, intel may drop some prices as well.