Loch Ness Hogmanay takes place in Drumnadrochit - and there tends to be several days of things going on from the 28th December through to Jan 2nd. including stuff for kids, live music , guided walks, etc.
On New Years Eve (Hogmanay) itself there is a live pipe band, live music, lone piper at midnight and fireworks. Its a small event but perfectly formed - with more and more people coming every year but still retaining a 'local' feel where you end up knowing everyone there and is family friendly!.....and its free but donations are welcome as it helps pay for next years event!
Note - this is an outdoor event so dress for all eventualities! The first year it was dry and crisp - last year it bucketed down...but on the plus side there is only so wet you can get and it encourages you to dance all night! (even if you will be 6 months pregnant!)
For indoor events - most of the hotels will have their New Years Eve package which will usually include some form of entertainment as will some of the restaurants. You will probably have to book in advance for all of these.
RE Pubs - in Drumnadrochit, some will close their doors at around 10 / 10.30pm (ish) with no re-entries so if you want to stay indoors get there before this time.
Stay local to where you want to celebrate if you can - I know that you wont be drinking (and NO ONE should ever drink and drive) but keeping cars off the road at Hogmanay can only be a good thing.
The other villages around Loch Ness will usually also have something on - but not on the scale of Drumnadrochit. It will usually be based around the pubs / hotels.
I have no idea what will happen this year in Inverness but Im sure that someone else will be able to tell you what they are doing for 2007-2008 (But I doubt it will be as much fun!<grin>)
More info: www.visitlochness.com for events etc.
Whatever you choose o do - I hope that you have a wonderful holiday !