Power supply experts, can you help?

I'm in the process of upgrading my HP Pavilion into a gaming computer. I have the a6228x model, and plan to add 1GB RAM (Totaling 3GB), case fan, 8800GT, and a new power supply. I am completely stuck on the power supply.





First of all, I only know that I have to get an ATX, not an ATX 12V (difference?) I've been looking on newegg and in my list of ATX's I found a couple that were ATX, ATX V2.2, and ATX V2.01. Is there any difference between these?





Also, my motherboard has a 24-pin power connection, but my 250W stock power supply only has a 20-pin connector. If I get a power supply with a 20+4 pin connector, would plugging in the extra 4-pin damage or enhance my performance in any way?





Also, any good reliable companies? I went through the site and I narrowed it down to like, 10. You don't have to pick one out, but if you could, could you remove any eye-catchers as possible problems? Thanks in advance. Please I need an answer, especially about the 24-pin. 10 points to best answer.
Power supply experts, can you help?
All the ATX v2.2 and v2.01 stuff are just different standards in power supplies. You should also buy a PSU that is at least ATX v2.01 compliant or higher. These are made to be backwards compatible with older systems that have only a 20-pin power connector.





I recently got a new PSU also with a 20+4 connector, although I don't know how it was plugged in considering my dad installed the PSU.





One good reliable company that makes power supplies is Antec. Although you may not see Antec listed as a manufacturer on the search in NewEgg, go ahead and search "antec power supply" in the search bar. It will bring up all power supplies made by them. Hope this helps. :)