Access Virus is virtual analogue anyway, so yes - plugins can sound that good.

In fact, I understand you can get an Access Virus TDM plugin for Pro Tools, which uses identical algorithms to the hardware version - not sure if they have released / will ever release a VSTi version though.

On the other hand, with the Virus TI you get a dedicated DSP chip for synth duties (i.e. no load on your processor) plus a control surface and an audio interface into the bargain.

So, swings and roundabouts.