Looking for a Case for micro-ATX motherboard, any suggestion

I am looking for a Case for micro-ATX motherboard
and also a PSU (about 550W) for my GeForce7800 GT

I have a OME sony vaio computer... they put everything into a small case... recently I brought a GeForce7800 GT which needs at lease 450W PSU when I try to change a PSU, I found that I dont have enough space for any other kind PSU, So I have to cahnge a case too

Does anybody have any suggestions for a good case and a good PSU?

I see there are lots of cases which can work with m-ATX motherboard
But I'm afraid that the case will be too big for my motherboard

Or Should I also change my motherboard to a regular ATX?
Any suggestions? Will those motherboards which have chipset better?

I am a newbie... this is my first time building my own PC
Can anybody tell me what to do

First of all, thank you for replying.

Now I have
mATX board with Intel chipset ( OME product)
Intel Pantium 3.0 Ghz ( not so sure about other stuff)
512MB RAM
200 GB hard disk
EVGA GeForce 7800 GT (not using yet.. b/c i dont have a good PSU)

Now I am just planning buying a new case and PSU
I will due with the motherboard later...

Any good suggestions?

I am looking for a 500W or possibly higher, like 550W PSU

Since I have a video card which needs at least 450W

So ur suggestion may not work for me

I am not worrying about my mohterboard now
since i can change it if it doesn't fit

But Thank You though

I find out that, when you buy a case,
most of them will come with a PSU,
and it will be cheaper compairing buying them separately. Isn't it?

Does any body have a good suggestion what combo works good?

might I suggest a aspire X-qpack with a 420w power supply? heres the link to the newegg listing of it http://www.newegg.com/Product/Prod [...] 811144109.