I have a hp pavilion slimline s3700f. I'm not sure how outdated it is from computers these days, but I put a new graphics card in. A HD Radeon 4350 for like 100 dollars. Anyone have a guess on how much I should sell it for?

If its nice and clean I wouldn't expect more then $200 - $300 usd for it.

Also check eBay and other places to see what they are selling for.

You should be able to get two to three houndred bucks for it, I have been building computers for a very long time and shell life of computer this days are just like a car, once out of the lot is worth half the value.

you should sell it as a basic entry level computer for browsing the web and e-mail I'm sure it can't not handle hight loads of graphics.

Since you have built computers. I'm trying to build mine and I'm worried that the things I buy will not go together well or will have errors and the drives and software isn't on it. Do you just install the disks that come with the stuff?