Hi guys, I need some help and suggestions with a computer upgrade I will be doing for the first time in my life.....
I've been studying computer builds on Google, and i thought experience is better than simple knowledge that i got from studying on Google, so here it goes.

I'm trying to upgrade my computer in graphics.
My current Specs:
Computer: Acer AM5100-U5201A (Micro ATX i believe?)
CPU: AMD 64 X2 4400+ at 2.2 Ghz
MOBO: AMD 690G with Socket AM2 with 3ghz max CPU speed WITH a PCIE X 16 (Not a 2.0 PCIe THOUGH could be bottleneck?)
GPU: (built-in the MOBO) RADEON X1250
PSU: a mere 250 watt. Stock.
RAM: 3 gigs

I want to get a 9800GT from MSI
http://www.newegg.com/Product/Product.aspx?Item=N82E16814127381

but i need at least 400w for that card so im getting it with a 500 Watt Apevia (good company?)
http://www.newegg.com/Product/Product.aspx?Item=N82E16817148038
it has dual 12V rails [emailprotected], [emailprotected], which I think meets the requirements for the MSI 9800GT

First Question is that could my current spec be bottlenecking this upgrade? My MOBO is old and small and my CPU aint bad but I just want to ask.

2nd Question: MOBO, CPU, GPU, and PSU compatibility. Basically if you have a 4 pin for CPU and 24 pin for MOBO connector, it is compatible for the MOBO and PSU right?
And I will need a 6 pin PCIe connector for my GPU which I already get with my PSU.

3rd Question: Size??? I get about 8 inches for my SATA ports to stay open. But if it is a single slot, i dont think it will block my SATAs as long as its not thick. Problem is that this card is a dual slot. I dont know the exact dimensions of this card, but it looks like a standard, long card... which usually are about 9" long?
Pictures:

http://i402.photobucket.com/albums/pp108/Speairs/DSC00173.jpg
http://i402.photobucket.com/albums/pp108/Speairs/DSC00176.jpg
http://i402.photobucket.com/albums/pp108/Speairs/DSC00177.jpg

PSU size: My current PSU size is 5 3/8" x 5 7/8" x 3 3/8" LxWxH with possible human ERROR...
The one i am going to buy is 5.5" x 5.9" x 3.3" (L x W x H) Which is REALLY close to what my current is...... should .2 inches matter in fitting a PSU?

Pictures:
http://i402.photobucket.com/albums/pp108/Speairs/DSC00171.jpg
http://i402.photobucket.com/albums/pp108/Speairs/DSC00172.jpg

I know this is a very selfish and long post guys really sorry..but i really need help on my upgrade1. That spec shouldn't cause a major bottleneck.
2. If the PSU provides enough power and has the right connectors, it's compatible.
3. The 9800GT is about 8-9 inches long. You could buy a single slot card, but in small cases it might still cause problems. From your pictures I think the card would fit, but only just.

A powerful video card throws out a lot of heat, and in a small case like that there's not gong to be much ventilation. I'd recommend you buy a new case, or look into improving the cooling on that one. Any fans in the ase currently? Any space to add more fans?

I'd also recommend you choose a different PSU - after rebate, this better quality OCZ unit is $5 more.I do currently have an exhaust fan right by the CPU Fan, 120mm really slow but quiet, but i think can attach another one if i have to right on my case door because there are grills with holes there.

As for the PSU, as long as it is an ATX PSU, is it guaranteed to fit in any ATX case? because my Acer is i think a mATX?

http://images.tigerdirect.com/skuimages/large/Acer-Aspire-M5100-A180-5100.jpg

But my stock PSU is very close in dimensions to the OCZ PSU you recommended me
OCZ: 150 x 140 x 86mm (W x L x H)
Stock: 5 3/8" x 5 7/8" x 3 3/8" LxWxH ATX PSUs will fit in any ATX case. Your PSU sounds very close to ATX standards, not sure if another will fit or not.
You might want to ask Acer about that.
As for ventilation, two 120mm fans, one front and one back, should give enough airflow for a decent card.Thanks for the advice
Although i cant add a fan to the front theres really no space for it...
As for the PSU i mailed Acer

and i found another similar card but it has better cooling on it

Better cooling:
http://www.newegg.com/Product/Product.aspx?Item=N82E16814127379

A little bit overclocked version:
http://www.newegg.com/Product/Product.aspx?Item=N82E16814127381

Which do you recommend? they are pretty much the same except in cooling vs Overclock

I made a paper model of the width and the LENGTH only cause the height dont really matter:
http://i402.photobucket.com/albums/pp108/Speairs/DSC00179.jpg
http://i402.photobucket.com/albums/pp108/Speairs/DSC00180.jpg
http://i402.photobucket.com/albums/pp108/Speairs/DSC00181.jpg
http://i402.photobucket.com/albums/pp108/Speairs/DSC00182.jpg

Length was 220mm and width was 33mm (because its dual slot)
Blocks only 1 SATA port out of 4, and i only plan to use 1 HD so i think im safe for the fitting
Well, it's up to you.
I would not have a 9800GT in a case without any air intake myself.