These 2 apps combined are so complimentary as the CPU amd HDD's appear to work separately from the DSP cards still.
GS4 has the ability to go XP32 / XP64/ Vista 32 / Vista 64, and is currently hosting my Kontackt instruments also.
I love Kontackt romplers but when doing FM8 layers w/ Celmo's Bluewave, or any Scope based instrument the latency drove me nuts.
Gigastudio operates it's MIDI at the kernel level and the ULLI of Scope w/ GSIF is awesome.
Even w/ Kontackt 3 being 64bit I will still use GS4 as the VSTi / VST FX host as it allows those great romplers to sound and perform better.
It sounds better, and loads tons of content just w/ the 3GB PAE.
I cannot wait for XITE-1 so I can load 8 GB's of RAM and go to XP64. Fuck Vista, it is not 4 me.
My dream DAW is very close now.
