This is an unfortunate and common issue with display devices that perform any form of input processing (sharpening, noise reduction, dynamic contrast/colour etc). My monitor introduces around 180ms delay (measured with Guitar Hero, which is naturally unplayable on the monitor).
If you run the audio through the TV the TV will delay the audio to compensate as it knows the picture will be delayed - if you connect a receiver to your PC for audio you may be able to introduce a delay via the receiver, though that's an expensive hardware solution for something that could be handled in software.
It may be worth checking your TV's menus for a mode that disables input processing and reduces the delay. My monitor has a "PC" mode which reduces the delay, but this only works in 60Hz mode (switching to 24Hz/50Hz for Blu-ray/PAL content disables PC mode and reintroduces the delay).
I agree that it would be nice for PowerDVD to offer an audio delay feature as it shouldn't be too tricky to implement (other software such as XBMC and ffdshow support it) and it is invaluable when dealing with lagging display devices.