I have two WinTV-GO cards in addition to a PVR-250. I really wish it would accept a GO card. I know it couldn't have hardware MPEG2 encoding, but it should at least allow you to watch something else on it live without recording in case you have another program recording with the PVR but feel like watching something else live. Sigh... I can dream.
Haven't tried this yet, but you might be able to launch a CustomTask to launch WinTV2000 and use that to watch on your Win TV GO, while the PVR150 is recording.
I have a GO card as well, and might actually try this (I also have a LifeView Walker Ultra which I use for recording with GBPVR).