Emmt,
I went to Namibia a few years ago and had a great time. I've also been to South Africa but found that a bit "touristy". I was there for about 3 weeks, flew from Paris to J'burg and then to Windhoek.
I was staying with people who lived in Swakopmund so we based ourselves there and did a few trips. Went camping in a Leopard park - sorry I can't remember any names of the places at the moment. That was cool, the main camping area had a load of animals living there, these were animals who had been injured when young and were taken care of by the owners of the campsite.
We also camped at a mountain (Brandenburg I think it was called) and climbed it the next day to see all the really old cave drawings.
Spent a few nights at a safari lodge and got to see loads of wild animals - believe it or not I thought the elephants were probably the scariest as they came running after us! I'll try to dig out the name of the lodge but I know it wasn't in the "main" safari park. At night time we went to watch the wild lions being fed - that was really scary as we were just looking through a gap in a wooden fence. The park people put out fresh zebra meat once or twice a week so the lions knew where to go for food.
Back in Swakopmund/Walvis Bay we went sandboarding and quad biking on the sand dunes - the views were amazing. Swakopmund also has a decent enough nightlife, pubs, clubs, restaurants, casino etc but as females we found it wasn't particularly nice to be out without a man in the group, otherwise we just got hassled so much.
Will try to think of more stuff. I found it incredibly cheap. Most of the time we had somewhere to stay but camping and the lodge cost very little. Food and drink were unbelievably cheap - even cheaper than South Africa. Flights cost around IRE£600.
The lonely planet guidebook was really good and fairly accurate at the time - you should take a look at that.
Shots are the same as for South Africa so you should be covered for most (well, the ones that you don't need a booster for after a year).