Is there a decent pci express half height graphics card

what games are you wanting to play?

Given your 220w PSU, the HD 5570 would be the best card to choose.

Whether it is powerful enough to play the games you want at whatever resolution you want is a different story.

My son likes to play World of Warcraft,while I play Diablo 2 LOD. I am afraid the new Diablo 3 will not run well with the current graphic set up. I don't expect blazing speed as the computer I bought for my son has a Phenom Quad core. But for the times he visits and is unable to bring his cpu along, I would like him to at least be able to play reasonably well without error messages, etc. And the previews for the soon-to-be-released Diablo 3 look comparable to WOW graphics.

I never played WoW and I don't think the system requirements for D3 has been released.

See following link for some gaming benchmarks. Note that the test rig uses an Intel i7-920 CPU so benchmarks on your PC will be a little lower. But given the

http://www.techpowerup.com/reviews/Powercolor/HD_5570/6...

I would really like to find something that will fit the PCI Express x 16 slot with 1 GB, and while I have run across the Sapphire Radeon HD 5570 - 1 GB DDR3 DP/DVI-I/VGA PCI-Express Graphics Card 100293DP, I am not certain this is considered a low power half height card. It refers to being a low profile card, and I have seen some people saying that half height and low profile are not the same thing. In addition, I have seen mixed reviews on whether the 220 w PSU will be enough to run this card. Again, I am not looking for perfection from an eMachine, but I don't want to mail order something that will not work at all. Price is not a huge deal, but $50-100 seems a reasonable range for an item of this ilk.

it may be worth looking at getting a standard sized case and 500~ watt PSU, that way you can choose just about any graphics card you like (within budget)

And I forgot to mention that machine runs a 64-bit system. Would a new case and PSU be as easy to change as I am thinking?

It is fairly easy. Below is a 31 minute video about how to assemble a computer. You can skip many of the steps since you are basically going to transplant the components from one case to another case. That means it is no necessary to remove the heatsink and CPU, and the RAM (memory chips). You would simply need to unplug all the cables from the motherboard and remove any attached cards like a sound card.

http://www.youtube.com/watch?v=ot0h4G-BmJM&feature=rela...

I did not look at the entire video, but I notice the person attached the video card to the motherboard before inserting the motherboard (CPU and RAM as well) into the case. Do not do that. Install the video after the motherboard has been screwed into place and after all the drives have been install. Just in case the video card blocks you from installing a hard drive.

Best i could find for you.
Says it "wants" a 300watt power supply, But i think it may still run fine. worst case you have to buy a 30-40$ 300-350 watt power supply.

http://www.newegg.ca/Product/Product.aspx?Item=N82E1681...

If you actually do decide to buy a case, power supply and video card, then you need to come up with an overall budget. The price of the video card can become quite expensive depending on the level of performance you are looking for.

As the link to the game benchmarks I provided above, gaming performance is directly related to the resolution you play games at. The higher the resolution, the slower the performance which ultimately means a more powerful video card is necessary.

I did review the TechPowerUp review and that looks like a good comparison. In addition, I looked at dormantreign's product suggestion. Just to be sure, these suggestions will work with this: http://www.emachines.com/ec/en/US/content/model/PT.NCG0...
and I have the options of trying the card with a possible PSU upgrade and/or changing the case and PSU as HugoStiglitz suggests and as is fairly well outlined in the video jaguarskx suggests. I want to do this once and be sure I consider options and pricing. I normally order from NewEgg and TigerDirect. Any preferences among you helpful guys?