I think now is the time for my to do some research on lenses too, I'm looking to do portraiture / band shoots for promotional material which effectively could cover wedding photography too. I know I'm going to have to purchase at least one lens with the new body as I can't take all my photos on a 50mm fixed lens.

Phil I noticed you mentioned the 7D, isn't this limited as it doesn't have a full frame. If I'm mistaken or missing something then let me know. I'm just now needing to learn more about the technical aspects of camera as its a lot of money to spend and I want to get it spot on.

All Nikon lenses fit any Nikon DSLR camera, you can also get converter rings for Canon lenses to Nikon to Canon so no need to part with existing lenses. So the real question is the camera body.
Do you want to stay with a make your familiar with?
Which camera is more comfortable to handle?
Cost?
Specification

No one can actually say this or that camera will suit you best, we all have our own preferences. All I would say is try out both before deciding.

Bazza

Take a look at those threads in my links - Tommy does some band photography, they have a real pro feel to them. Bear in mind you'll need to budget for lighting too... that makes a world of difference

It's a kind of juggling act. Whilst more MP has advantages - it's just part of it as 'in theory' - the lower the pixel density - the better the camera will handle noise. With that in mind, these 3 cameras kind of go in three very different directions.

Few on Big
The D700 has 'just' 12.1 MP but on a large full frame sensor 36 x 24 mm (8.64 cm²) so the pixel density is down at 1.4 MP/cm²

Lots on Big
The 5DII has the most pixels at 21 MP again on a large sensor 36 x 24 mm (8.64 cm²) so the pixel density is up to 2.4 MP/cm²

Lots on Small
The 7D falls in between with 18 MP but on a small cropped sensor 22.3 x 14.9 mm (3.32 cm²) so the pixel density is much more crammed in at 5.4 MP/cm²



Whilst Full Frame tends to be seen as a step up - a lot of people prefer Cropped sensor cameras.

People who like to photograph sports, wildlife, motorsport etc may decide to keep using cropped sensors. You get a little extra reach with the same lenses and the camera tends to shoot more frames per second.

People who like to photograph landscapes, still life, architecture etc will be less concerned with speed and long focal lengths and go for a full frame camera for it's image quality and ability to shoot in lower light.

I've stuck with my 40D for now and have only had a bit of use with these cameras but I'd say (and it is my just my opinion) that the 5DII is full on landscape lovely - the 7D is more action - the D700 is the all rounder.

If you go full frame then lenses do come into it. When you stick a lens on a cropped camera - the sensor only records the part of the image that is coming through the best part (middle) of the lens.
When you stick a lens on a full frame camera - the sensor records what the whole of the lens sees. Image quality is at it's worst at the edge of a lens which is why you can often get away with cheaper lenses on cropped sensor cameras but are worth investing in better lenses (sharp at the edges) for full frame.

Anyway - that's enough 'geekiness' for one night.

Fantastic feedback guys, I've got a lot to think about. It will have to be a case of building up my arsenal as I go I think. I wont be able to afford lighting kits off the bat, my 430 EXII should fit should I go the canon route so Its not light I'm completely out of light at all, that and I can afford to shoot in a lot darker situation due to better iso/noise handling on the better models.

I LOVE my D700. I upgraded from the D50 to the D200 and then the D700. I love the handling, the build quality, the fact that the ISO is amazing, and also the available Nikon dedicated editing software. I shoot portraiture with mine and its perfect. Its light enough to handhold and with that ISO output you can do without a tripod in alot of other situations . xx

Initially its going to a body & lens, I'm looking to shoot bands as mentioned previous so I'm looking for a relatively wide angle lens, any suggestions?

They are both going to require expensive Pro quality glass to get the best images.

Don't just go by specs. Canon tends to overstate their cameras abilities while Nikon understates theirs.
The D700 has more than twice the high ISO capability.
The 5D2 can produce a better picture up to ISO 1600, above that the D700 easily wins.

The D700 is much easier to use and more forgiving of user error due to lower pixel count, better focusing, presets, and ergonomics.

However, I expect that the user is fairly proficient in the Canon system after "outgrowing" a 350D.

I suggest that he get his "hands on" both cameras before deciding.

Good advice there Roger - having a play with the cameras is a really good thing to do and for most people you'll know instantly which one you prefer

Depends on how close you can get to the stage.
You might be able to use your "nifty" fifty.
The fast aperture is very desirable.

I would probably show up with a 70-200 f/2.8 mounted and bring a 24-70 f/2.8 along.

If I could afford it, I would use a Nikon D3s with 200 f/2.0 lense.