Looking to get a new case (transfer over my old stuff)

[SuxoR]

Hey guys well I wanted to get a new video card (probably a 4850 or 70) I'd have to get a new PSU and the card wouldn't fit the in the stock case I have (Acer Aspire m5100)

I'm looking to transfer over my current system and upgrade it slowly over the next year (yes I'm a poor college student)

What kind of case should I be looking for? Mid size? Are full size overkill?
Eventually I wanna get a really nice system going but not too insane

I want a good looking case side panel if possible with great cooling that will last


Any recommendations? Not looking to spend too much 100 or less I guess

Thanks guys
some of the bigger stuff inside (specs)
Processor:
AMD Athlon(tm) 64 X2 Dual Core Processor 6000+ (2 CPUs), ~3.0GHz
Hard Drive:
ST350000830AS ATA 500 GBS
Video Card: NVIDIA GeForce 8600 GT
Sound Card: Speakers (Realtek High Definition Audio)