As for *minimum* requirements, it seems like it will be about the same as GS 2.5, as fas as sample playback goes. For the additional features you\'ll need a GSIF 2.0 driver for your soundcard and maybe for your MIDI connection. And you\'ll want more horsepower for the DSP effects. Of course more/faster disk drives will increase your sample throughput.
Oh, one difference for 3.0: I think XP is required.
But if you have an XP box running 2.5 today, I\'ve heard nothing that implies that it wouldn\'t run 3.0 tomorrow.
GS3 was written and optimized for Windows XP. BUT, It will run on a windows 98 or 98SE machine. I specifically asked this question at NAMM. Also.....running GS3 on older machines....one will NOT take a performance hit. You will at least have the same polyphony as you did in GS2 on say a Pentium III (just with the added GS3 features and more stability in the program).
Where a fast machine is needed to run is when using GigaPulse. They said basically a 2.4GHZ Pentium 4 with as much RAM as you can to run the convolution reverb of GigaPulse.