wich should i buy

im not good with comparing computer but since i've noticed that most of you guys here are great with computers i thought this was the best place to ask wich of these computer i should buy i dont have alot of cash right now and i dont want to spend that much since im saving for a car (im 16)

Too hard to choose!

i cant post the computer specs for some reason it says -tag span may not have attribut id

just summarize, etc

core 2 duo 2.8ghz

2 gb 667 memory

450w psu

radeon 4850