I use it on a Fujitsu Core2duo with 2Gb Ram, but I use that computer as a source to record with another one, so I can't really tell you whether it works fine when you open 10 Gearbox instances...
But I do recommend the GoldBundle, which has many more effects and amps.
It's a very good alternative to POD 2 or Pocket POD, but certainly not PODX3. Its great advantage is to be able to use it with a Toneport to record vocals, basses or something else other than guitar.
You can use it with the packs (metal shop, FX junkie, collector classic, and gold bundle) to have dozens of amps and pedals. It's been 3 months since I have it but still haven't explored all possibilities! It's truly incredible.
However, it's impossible, or virtually impossible, to use it live, it's for studio only. Live, you need to couple it with an amp or a POD X3!