Ok, I switched from Cakewalk to Cubase SX cos a mate told me it was way better, but, I cannay get the ****in' thing to work. I'm using a GuitarPort and all the hardware is set-up corectly because I used it with Cakewalk, but Cubase won't register any sound at all. On the devices list the VST device is ASIO GuitarPort, which is what it the manual said, the control panel is there and registering that it's working with Cubase but I'm getting nothing.

I've exhausted my rather limited knowledge so can anyone help me?

Much appreciated, Matt.
If I'm not wrong you've got to have a memorystick with serial-key on it to unlock this version of Cubase... pretty tough security-measure's

BUT... there's still some hope left!

If you want the version without the serial-datastick-key you need to download Cubase H2O (O, like the last letter of Hello... )... this is the hacked-version

good luck (p.s. you can download it from torrentspy.com with Azureus )
when you set a track to record have you selected the input of the guitar port in the left hand 'inspector' window?

Have you done the following:

devices>>vst connections>>add bus>>find your tone port bus and add it

then at the left hand edge of the screen, drop down the topmost menu of the inspector and select your newly created bus as your input.

try that, more details in the manual.
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