I want to buy one of the followings but don't know which one is any good. Please help.

System 1- $220
-AMD Athlon 64 3500+ socket 939 w/ Artic Silver
-MSI K8N-F SLI Premium
-1GB Dual Channel Kingston PC3200
-ATI Radeon x300SE
-250GB Western Digital Caviar 2SE SATA
-Antec Quiet EarthWatts 380W (EA 380)
-X-BLADE Gaming Case with Clear Window and fans
-Windows XP Media Centre 2005 Edition w/ COA
-BenQ Super Multi Burner (20x)
-LG DVD Drive
http://toronto.en.craigslist.ca/yrk/sys/750820258.html

System 2- $450
-ASUS A8V-E SE (socket 939, PCI-E slot)
-AMD Athlon64 3700+ (2.2ghz, San Diego Core)
-2GB (2x1GB) Dual Channel OCZ Platinum (2-2-2-5) PC3200 / DDR400
-EVGA 6800GS (256mb DDR3 PCI-E)
-Antec Sonata III Mid tower
http://toronto.en.craigslist.ca/tor/sys/751112378.html

System 3-$350
-250 GB hard drive
-SiS Ultra256 2D/3D Graphics Accelerator
-Logitech wireless/cordless gaming mouse and keyboard
-ADI AD1888 6-channel 3D audio
-Onboard 10/100 Network Card
-450 Watt Power Supply
-1285 Deluxe Black Tower Case
-20X DVD/CD BURNER
-AMD Sempron 3000+ Processor
-ATI Radeon EAX1EAX1550TD 256MB
-ECS Motherboard
-1 GB Memory
http://toronto.en.craigslist.ca/tor/sys/749083823.html

System 4- $450
athlon X2 3800+ CPU
X1600 PRO 512 MB!
2 gb of ram!
250 GB HDD!
WINDOWS VISA HOME PREMIUM SP1
lots of software included
microsoft enterprize 2007
ADOBE CS3 master collection
http://toronto.en.craigslist.ca/tor/sys/738620374.htmlthe best looking one so far is system number 4, however, the seller is not LISTING his RAM type, mobo make/model, or power supply.What will you do with the computer? Internet? Game? Office applications?

Are you looking only at used systems?I am buying it mainly to play games that are obviously not new released but a YEAR or so old.