I get 99% of my computer and supplies from Newegg and have had really good luck with them.
http://www.newegg.com/Index.aspx?name=Home. They are located out of CA.
Be careful about what operating system your new computer will have since some of your regular programs/games that you like to play may not work on the new system.
I am not a fan of DELL. My 1st computer was a DELL and I'll never buy one again. I know several people who have had problems with them, and I know several people who love them and have never had any problems!
It is also cheaper and easier to upgrade a non-DELL computer such as video card, power supply, memory, etc., if you decide to, down the road.
Good Luck