Ok - my brain is about to explode with all the permutations but here's what I am thinking after some research:

- I could leave my 350Gb int drive alone, as i have at the moment for boot and apps. Any benefit to partitioning this and using some as a scratch disk for photo/video editing or should another drive be used for scratch - i'm guessing i should use a separate drive but wanted to double-check? It's just that 350Gb seems like a lot of space is being wasted since I won't be using anything like this for apps - I'm a minimalist kind of guy!

- The 750Gb could be used for video (which is secondary to my photography - currently just getting into HD video with my 5d2)

- My understanding is that currently, 1Tb is the max size for Mac pro int drives. I could get 2 x 1Tb drives and these would me my Photo and Lightroom Catalog/Thumbs etc. storage drives. These could be RAID 0 striped as well couldn't they - to make them even faster right?

- Technically the slowest drive I have is the ext WD 2Tb My Mirror USB 2.0 (which I understand will need to be re-formatted for OSX - any tips?). This can be my ext back-up drive. This would be brought and taken off-site regularly. If I use this via RAID 0 Striped, not only will it it provide me with 2Tb as opposed to 1Tb of storage (RAID 1 Mirror which is how it was set-up on my Windows Laptop), it will prove faster for back-ups right?

- I'm thinking Time-Machine/Chronosync for backing-up - read good things about them on www but can't seem to work-out why i would use both at the same-time as some do.

Although I have had a 100% digital photography workflow for 2-3 years, on my desktop PC (8 year old AMD Athlon 850Mhz / 20Gb hard drive / RAM don't even ask!!!) which was recently consigned to the grave, there was no hardware/optimisation knowledge on my part.

My very recently purchased laptop (Dell Inspiron 1545 Dual Core 2Ghgz / 3Gb Ram / 250Gb int drive) was sold to my sister in law to fund the Mac - the RAW files from my recently bought 5d2 made my 20d files look like play-school! Things were already slugging-along with the 20D's 8Mb or so files...imagine what 20-40Mb files did!!! Don't even mention LR local adjustments!

So with about £1,800 to spend, and various sources/instinct telling me to buy a decent spec second-hand Mac, to go with my already acquired second-hand Eizo CE240W monitor (i love that thing - can you tell?) here I am 2 days later - with an unfamiliar computer, with a different OS and lots of technical storage/hard-drive configuration decisions to make....

Exciting - yes. Mind - boggling - OH YES. Scary - just a bit!