Is my upgrading good?

I am only upgrading:

Evga 8800 GTS 320mb GDDR3 video card

G.Skill 2gb DDR2 800 ram

AMD Athlon 64 X2 4600+ 2.4ghz duel core

Seagate Barracuda 250gb HD with 7200 rpm

And I am keeping my motherboard and sound card but i need help choosing a new case. Can anybody suggest one -100 dollar range.

By the way ill tell you what im upgrading from.

AMD 64 Athlon 3200+ 2.1ghz

128mb GeForce 6600GT

1gb of cheapo ram

and a 111gb hd

Make sure your motherboard supports the new CPU and RAM. Is it socket 939 or AM2? Big difference! Also make sure you have PCI-E slot for the video card.

You may also need a new motherboard.

how do i find out what type of motherboard i have

You can use CPU-Z...

http://www.cpuid.com/cpuz.php

Also, for a $100 ish case with agood qualityPSU for that system, you could go with this:

http://www.ncixus.com/products/24294/SONATA%20III/ANTEC/

is it if i have an AM2 i can use AMD chips and 939 for intel? cause im upgrading from and AMD to a new AMDXyphereos

No socket 939 is the predecessor to AM2.