Hi, I'm faced with the same dilemma so I searched google for the answer and found this. I know this is an older post, so hopefully someone will find this and respond.
First off let me explain my background. I have a 2 year old system that I built at first for gaming. Later my Mac died and I didn't want to buy another for my auido purposes, so I converted the gaming PC into my audio workstation. Recently my mobo died (AM2 mobo), so I have decided to go ahead and make a few upgrades instead of buying another AM2 mobo. I'm upgrading to an Asus AM3 mobo, Phenom II x4 840 3.2Ghz processor, and my last upgrade will be memory. I don't know much about how the memory acts with audio processing, so I'll just explain what I use and a problem that I had before I'm upgrading.
I run Cubase 4 as my main DAW (Digital Audio Workstation). Connected to the computer I have a Firewire PCI card so that I can connect my Tascam FW 1082 DAW controller (kind of like a mixer, but lets me control Cubase controls as well). I also have a keyboard (MOTIF XS 6) connected via USB to the computer for the midi signals. The all audio from mics and the keyboard connect to the TASCAM.
On my previous system I ran an AMD Athlon 64 3800+ processor and 3GB of RAM 2 X 1GB and 2 X 512, both Dual Channel. Whenever I would open up virtual instruments (VSTi) in Cubase (specifically Omnisphere and Kontakt 2), the system would hesitate and take roughly 60-120 seconds before it would actually open the VSTi.
If the track was playing in Cubase during that time, it would skip, stop playing, play again, skip, stop, etc. until the VSTi was opened. Once open everything ran smoothly. I don't know whether this was a processor issue or a RAM issue, but I'm trying to combat both areas just in case.
The mobo that I'm getting (due to the fact that I need a PCI slot for the FW ports) only has 2 DDR3 memory slots vice the usual 4. So is it best for me to get a single 4GB memory stick, or 2 X 2GB Dual Channel sticks? I'm thinking the single 4 may be best for the price that I can use to get another in the near future when I can afford it rather than getting the dual 2 and having to replace them both later to get dual 4s to get a total of 8GB. Please let me know your thoughts. Thank you in advance.