It'd be most beneficial if 6-9gb would be big enough for the files you are using so you could drop them in a temporary RAMdisk.. When I work with RT7-Lite, RT7-Booster, MKVToolnix(?), Handbrake, Adobe Premiere/Photoshop/Illustrator, etc# it helps tremendously. Even if I just swap stuff around as I am actually use it. If not I'd check to see if it has any options to enable you to allow the program to use more RAM - much like Photoshop allows you to do. Not having a HDD had might impede that however as transferring to and from it had might be more cumbersome.
I'd recommend putting $100-120 towards a nice SSD 90-128gb SSD ($60 could get you a 64gb M4 though) first though as that'd give you a more widespread performance boost. Getting more RAM on top of that would be the icing on the cake. :P
I had used to have 12gb but I'm down to 8gb so I don't know how things will have to change but 8gb RAMdiscs were usually more than enough for anything I would do.
While you're at it why not try getting your CPU to 3.6-4ghz too(assuming you have a decent cooler)? On top of having a faster processor that should take your ram to around 1531mhz would which would give your RAMdisc a modest boost. I've had 2-3 1333mhz kits and all of them could hit 1530mhz just fine so I wouldn't imagine you having any problems there.
Edited by Ryleh - 6/19/12 at 8:49pm