Hey everyone!

I've been composing for a fair while now, and I've just received a commission that is going to require a serious upgrade to my existing kit.

My current studio inventory is this:

Akai DPS16 (16 track hard disk recorder)
Focusrite Penta (compressor/limiter)
RODE NT2 (Mic)
KORG Triton ProX
Alesis Monitor 1s
Access Virus KC
KORG Karma

I've been recording various short films and other bits and bobs quite happily. But this new commission is going to require a Gigastudio setup - as its massively orchestral, but without the budget for me to pre-programme it then take an orchestra into the studio. For equipment upgrades i have in the range of $6/7k and I would like to buy a system to solely run Gigastudio 3 Orchestra, and another machine to run a sequencer. (Possibly Cubase SX with an 01X mixer?)
I know GS with Rewire will happily plug into Cubase SX, is this as easy in practice as it is made out? I was also thinking about buying both systems from Carillon - is that a good idea?
The score for this film (it's a horror) will be contemporary orchestration (electric guitars, drums, synths) backed up by an approximated 90 piece orchestra. From all the reading I've done, the setup I'm thinking of seems sound.

Does anyone have any advice?