In the market for a used Mac Pro to trick out, where to start?

Hey there everyone!

I am in the market for a used mac pro. I have read about people doing basic stuff like RAM and SSD upgrades, to more more involved mods like GPU flashing and CPU swaps.

What is a decent Mac Pro configuration to start with that is the best combination of speed, graphics performance, and compatibility with future hardware upgrades?

I have been looking on eBay and craigslist (I am in Hollywood so production house's editing machines are always popping up on craigslist for decent prices) and seen a lot of 1,1 2.66 machines and random dual 3GHZ models

I do audio production and light SD video editing in FCP, will eventually get into at the most some 720P hi def editing

my budget for the base config before a SSD, more ram, perhaps a better graphics card, and some storage is around $1000-$1500

yeah looking at the prices the only pros in that price range are the 1,1 2.66 model

is the 1,1 pretty useless these days? what mods can you do to it?

thanks for the replies guys

The SP 2.66 Quad 2009 model looks like the one to go with

can you upgrade the processor in these models?

Also what is the possibility of future SATA III connectivity via a card or something. Does the mobo support it?

Alrighty guys, after much lurking and waiting I have picked up a quad 2.66 12gb ram 2 tb hdd 4870 graphics off of ebay for 1699.

Thanks for all of the advice. The mac pro forums seem to be the only group who is happy with their hardware and not caught up in the 6 month upgrade mentality that is the macbook air forum.