Hey everyone,
I built this PC back in August of 2009 and have only upgraded the video card in it since then. I want to do a little upgrading before BF3,MW3,and Elder Scrolls: Skyrim are released but haven't kept up with the new stuff that is out or will be out soon. So I came here for help

My current setup is as follows:
Asus P5Q-E
Intel Core 2 Duo E8500 3.16 Ghz
ATI Radeon HD 5750 1gb
4GB DDr2-SDRAM
Antec 450W power supply
I'm thinking the best way to go is to upgrade the core components. I would like to realistically spend less than $700 but could go a little higher.
I'm also considering another case because mine seems to have very poor airflow (the side has been removed for over a year to prevent the video card from overheating and producing artifacts)
Like I said, this will be mainly for playing games like the ones mentioned above, and probably ToR when it is eventually released. I would ideally like to play at 1920x1080 resolution.
Thanks!