The D50 is a superb camera, and offers stupidly good value for money.
Be aware that the megapixel wars are largely irrelevant to most users. Unless you're printing at poster size, you'll not tell the difference between 6 and 10MP. All the entry level DSLRs would serve you well, and will all be stuffed with features that you'll probably never use! For the record, the only feature that the D80 has over the D50 that might be of interest to you is a bigger brighter viewfinder - most of the rest is not going to help you very much in taking better photos.
I'd suggest...
D50 two lens kit (18-55mm, 55-200mm) (£528 from
www.warehouseexpress.com)
Buying these lenses later costs a fortune, whereas they practically give them away as part of the kit.
I'd also add a Nikon 50mm 1.8 AF D (£79 from
www.microglobe.co.uk) This is one of the sharpest lenses Nikon make, and dirt cheap. The advantage this has over the kit zoom lens is that it's 'fast' in all respects. The focussing is quick, and it let's in more light than the kit lens. This means two things - the D50 focussing system will be far less prone to hunt, and you can shoot at faster shutter speeds. For example indoors you might have 15th second without flash at 50mm on the kit lens, vs 125th second with the 50 1.8. This should help a lot with your current problems with missed shots, and you may not need to use flash at all!
Don't forget to budget for a memory card, and don't buy them on the high street (I tend to use Amazon).