Replacing motherboard on dimension 4550

[Dev]

I still have my old dimension 4550 and I recently made the mistake of not realizing that my motherboard only supports AGP 4x. I bought an ati radeon hd 3650 agp in hopes to play some tf2 with an fps that isnt below 30. I've already upgraded my ram, my psu and yet the problem occurs cause, well, my computer is a piece of crap. So I went looking around and I thought, "what if i replace my motherboard?" I knew motherboards go for alot but i was hoping that i would find something below 70. I found this:

http://www.ewiz.com/detail.php?name=MB- ... otherboard
ASRock 4CoreDual-SATA2

It's good cause it accepts AGP + PCI-E(only 4x though) cards so I don't have to feel like this HD 3650 was a waste. My question is that are there any things I have to check for compatibility for? i don't know SO much about computers but do psu's have to be compatible with the motherboard and stuff like that? I don't have money yet to buy a new cpu but does my pentium 4 have a specific model that makes it incompatible with other motherboards?

I also don't know what to do about that windows xp problem where it doesnt work when switching to a new motherboard..

EDIT: Okay, I did some looking around and I also now know I'm going to need a new case cause if I DO buy this motherboard, it will not fit in the dell case

[TerraFrost]

Motherboards generally only accept only a certain type of RAM and certain types of CPUs. You can't stick PC100 RAM in a motherboard expecting PC2700 DIMMs, for example. And for the CPU... it'd need to have the same socket connection, among other things. For example,

http://www.newegg.com/Product/Product.a ... -_-Product

Check out the Supported CPU section and the Memory Standard one.

In all likelihood, you're going to have to buy new RAM and a new CPU if you get a new motherboard. You could reuse the same HDD but, for all essential purposes, it is a new computer. Microsoft could probably transfer the activation to the new one but I don't have any experience that.

[Dev]

Ohh, I see. I upgraded the RAM to 2 512 DDR-400 sticks awhile ago so I think that's fine.

I looked at this case, it's $35
http://www.ewiz.com/detail.php?name=CA- ... Case-Black

About the CPU, are there any cheaper ones that you would recommend?

[Nuxius]

Microsoft could probably transfer the activation to the new one but I don't have any experience that.

Negative. Dev will have to purchase a new copy.