Is there any difference in system performance between 8 and 16GB's?

If you're not running a 64 bit system, the question is irrelevant.
If you're running 64 bit, then it depends on what you are doing. The performance does not improve from 8 Gb to 16 Gb if you don't need more than 8 Gb of RAM for the things you do.
You can check from the task manager how your RAM usage is when running average tasks you do. There you can estimate if you're short of RAM.

Asking questions like this, and the recent CPU thread of ours, I suggest you put your specs in the signature.

Jim, currently I'm just using 2GB's of ram but once hard drive prices fall - I will have a nice custom built desktop. And of course, my choices will be 4, 8 or 16GB's of ram. I certainly don't want the Swap file kicking in but on the same token, I don' want to be spending money on ram that doesn't get used. How do DAW systems that's configured with 8GB normally run? I won't be doing orchestration type of work or large cinematic type of work, just your run of the mill studio album recording. Also, do you know if adding more memory will help lower the latency since it gives programs more breathing room and helps those programs run faster - I wonder if that will too help with the latency.

Jim, currently I'm just using 2GB's of ram but once hard drive prices fall - I will have a nice custom built desktop. And of course, my choices will be 4, 8 or 16GB's of ram. I certainly don't want the Swap file kicking in but on the same token, I don' want to be spending money on ram that doesn't get used. How do DAW systems that's configured with 8GB normally run? I won't be doing orchestration type of work or large cinematic type of work, just your run of the mill studio album recording. Also, do you know if adding more memory will help lower the latency since it gives programs more breathing room and helps those programs run faster - I wonder if that will too help with the latency.

 
Hi Synthetic,
 
If you're not making extensive use of virtual instruments, you'll likely do fine with 8GB of RAM.
Adding extra RAM (beyond what you need) will have no affect on performance.
IOW, If you currently run 8GB of RAM... and the system isn't RAM-starved (it's running well), adding an additional 8GB (16GB total) won't improve performance (also won't affect latency).
Latency is determinded by two things: The audio interface and latent plugins.
Your machine has to be able to sustain the load at a given ASIO buffer size.
More speed means you'll be able to sustain greater loads (glitch-free) at a given ASIO buffer size... but (again) it won't allow you to achieve latency lower than what the audio interface and latent plugins allows.
Note that not all plugins are latent (add additional latency).