Which upgrade for video editing?

[Meirion Roscoe]

I recently bought my cube, after selling my imac, because it is a 
stunning piece of beautiful engineering.  I could have bought a new 
iMac with a superdrive and solved all my Pioneer dvr105 'inside outside 
hack' issues - but it wouldn't be the same. I've always wanted a cube 
and will probably always have one.

My problem is though, that most of my work on it, is video and photo 
editing.  As I am of meagre means (and obviously devoid of computer 
knowledge) I can't afford every upgrade on the market.  So where do I 
start?  My cube is a 450 with DVD and 20gig HD.  It has 1Mb of RAM and 
not much else.  More RAM I can probably afford, but which upgrade is 
going to help me cut down the time iMovie spends chuntering away 
exporting stuff?  A new CPU or a fancy Video card?  And whichever one 
it is - how far down the line do I need to go.  The DVD on the 
umbiblical sounds great if it will work with IDVD3, but do I need more 
muscle to get it to work efficiently.

Thanks in advance for even reading this!

Rossi