For video editing Intel is still superior to AMD.

Also you want to go for a quad core CPU over a dual core since having those two extra processing threads will have a massive effect on video editing. This is why I recommend against Apple because unless you get their $3000+ G5+ towers, you are only getting a dual core.

As far as socket type, it all depends on how future proof you want it.

Socket 775 is still a solid socket, but the road map for the processors is done. The Q9550 is the best quad core CPU out there for the 775.

The two newest socket types are the 1366 and 1156. The 1366 is the i7 Intel line, and the 1156 is the i5 Intel line. The difference between the two is that the 1366 uses tri-channel DDR-3, while the 1156 uses dual-channel DDR-3. Basically this means that there is theoretically less bandwidth in a dual-channel versus tri-channel, but in real world performance you won't see it. Also if you go tri-channel you have to do at least 3 matching sticks of memory, so the lowest you would want to go would be a 3x2 (3 sticks of 2 gig memory) for a total of 6 gigs. With dual-channel you would go for a 2x4 kit (2 sticks of 4 gig memory) for a total of 8 gigs.

Also if you know anyone that builds, do that over a Dell/HP/etc.. etc. Their storage upgrade options are shit.

Just throwing out random numbers I could build an amazing Intel i5 for around $600 without storage. From there I could get a Velociraptor SATA harddrive to use as the main OS drive, or a reasonably priced SSD for the OS drive, and then go with 1.5 Terabyte Samsung Eco-Green harddrives for $90 a pop.