J'ai un Gport et tu n'as pas besoin d'USB 2.0, mon ancien PC était en 1.1 et ça marchait. Quant aux plantages, oui parfois ça plante mais pas à cause de l'USB, c'est plutôt en fonction des programmes que tu utilises en même temps pour t'enregistrer...
specs officielles:
COMPUTER SYSTEM REQUIREMENTS
The basic requirement for GuitarPort is a PC with Windows XP, Windows 98SE, Windows ME or Windows 2000 installed, plus a Pentium III 500 MHz or better processor (Cyrix and K6 processors will not work with GuitarPort), and at least one available USB port (USB cable included). 128MB RAM is recommended. The PC must also satisfy these technogeek requirements: USB 1.1 and AGP Graphics; PC must be "legacy free" no ISA cards and all peripherals operating in DMA mode. GuitarPort can work with other Windows audio applications that support ASIO, DirectSound or MME. GuitarPort requires DirectX 8a and Internet Explorer 6 or better and both are included on the GuitarPort CD-ROM. When using GuitarPort hardware, any USB hub used must have its own separate power supply connection rather than receiving power from the computer only via USB.