First of all, I'm new to building computers so bare with me.
If you are a careful person, you should be able to build a computer. If you can take things apart, and put them back into working order, you can build a computer.
My current computer is nearing 6 years old and needs to be replaced badly!
OMG! Is it a Pentium 3 or an Athlon XP?
I'm looking to spend around 800 dollars. That's what seems reasonable for the type of computer I'm looking for.
Your $800 is plenty if you don't need pro-quality A/V and you are not an extreme gamer.
My resolution is 1680 x 1050.
At that resolution, and medium settings, you could even use a budget card.
The 5670 or 6670 with
GDDR5 (not DDR3) would do an OK job. They are selling for under $60 (after mail-in-rebates). These cards will not be future-proof, but will be cheap.
The next step up would be the AMD HD 6770 or 6750. This is the "lesser GPU" that people have linked to here. They are selling for about $110 after rebates.
The highest card that you would want to consider would be the AMD HD 6850. These cards are selling for about $150. You should wait until you have the Dell XPS 8300 and mesure the inside of the case, as some 6850 cards may be too long.
Although I have done quite a bit of research on computers etc and I like browsing through Newegg.. I've never actually built a computer before and I'm still wondering if I should just go with a already built computer from dell and then upgrade the graphics card.
If you do not enjoy tinkering, then you should just buy a Dell. You will be thankful if it brakes, as you can just send the whole thing back to Dell (after you switch back to the included video card). You can get an XPS 8300 with a i5-2400 at the Dell Outlet for
$610.
You can then buy a card off Newegg for $50-150, depending on what option you like from above.