Danny
Remembering your other
post I think you have other priorities than kit upgrades, look to maximise the use on what you have now. If you need more kit see if you can borrow first, then rent, then look at buying S/H and as a last resort buy new.
Your kit is really aimed at studio portraits so I would strongly advise (given your situation) to focus 100% on and leave the weddings alone until you have some income. Unless you get a booking when the borrow > rent > buy equation should kick in.
I have a D300 and I have used it at weddings (now my backup), not great in low light but perfectly capable, as is the D200 TBH. Remember pros managed to get results on D200s and Fuji S5 Pros until the D300 came out. The newer the camera the easier it gets and the more challenging conditions you can work it, but they are not neccessary.
If you want to get into weddings I would suggest looking at the whole kit as you are weak in the lenses and have no backup. On a really restricted budget I would be looking at a second body - D300/D200/Fuji S5 Pro and S/H Nikon 35-70 f2.8 and Nikon 80-200 f2.8 (even the push/pull is good). I got both lenses for under £500 a few years back, alternatively look for some S/H sigmas (make sure they as f2.8).
Plus if you are looking at weddings then Public Liability and Professional Indemnity Insurance is a must.