i'm into my home music recording. its starting to get a bit bogged down with so many multiple tracks running so i figured twice the ram would give me twice the number of audio tracks
If you want to be able to edit more audio tracks simultaneously then you need to increase the size/speed of your audio streaming hard drive. Increasing the RAM will allow you to run more virtual instruments/plugins but it won't help with multiple track editing.
Try and use a separate 7200RPM hard drive to record to/stream your tracks from. So you would literately save your audio projects to this separate drive. To save/stream the tracks/projects to/from the same drive that has the OS and app's will slow things down. It's a no-no in the audio computer world.
I can run 100+ tracks in Nuendo, like Cubase but for post production, from my 500GB audio drive. However I might struggle to run lots of VSTi's with only 3GB RAM. But I can run Superior Drummer 2, a few virtual piano's with orchestral Vi's and dynamics/effects plugins before I run out of RAM.
Check the meter on Cubase's transport panel, this will give you an idea of where your resources are being used.
What hard drive/s are you running and what audio hardware are you using?