Hi Frances,
IMNSHO, bigger is better for all that you are wanting to do; ie; especially any video work. Faster is also better, but the speed difference between the 2.16 and the 2.33 will probably not be that noticeable with the frontside bus speed of 667 Mhz. If the footprint on your desk is about the same for the 24" machine, and you can afford it, by all means go for it!!! Especially for graphics and video editing. There are models available with 256 GDDR3 SDRAM available, I can't imagine you'd ever need more VRAM than that!
If you're local Mac guy is a loser, then I would definitely think seriously about a refurb or a new one directly from Apple, along with AppleCare. That way, you are assured of at least 3 years of operation with support and repair from Apple, and can ship your machine off if it needs repair, and not have to deal with the disinterested local chap if your computer needs service.
And remember, if you need more storage, and have to take the HD included with the refurb iMac, you have a Firewire 800 Port on that, along with USB 2 ports, and Firewire 400, which should give you plenty of very fast connectivity to any external Firewire or USB drive, all of which are pretty cheap these days.
As far as RAM goes, it's much cheaper to get it from those links that are posted already in this thread, and it's relatively easy to install, and the guarantee is really the same! That being said, make sure you find out what's in the computer, most of those iMacs ship with 2 512 MB modules filling up both RAM slots. So, if you can have Apple load the RAM into a refurb, it may be worth it in the long run if you want the full 3 GB.
A lot to consider for sure, but take a deep breath...
I would definitely try to get the biggest bang for the buck (oops, Pound..) but take heed of your statement of "False economy" and get what you need!
Good luck, happy hunting, and all the best!
Chris K
