OK, I think when your backspace is unresposive, you can't hit F12 and even your enter key is broken, it's time to get a new board. Something cheap (in the £20-30 region) with media player buttons and a few hotkeys across the top would be great, I don't really want or need all this 'gaming' nonsense. So what's good out there?
Saitek Eclipse III? I don't like it personally, but it's apparently a very nice keyboard to use. I run around on a Microsoft Sidewinder X6, personally, but it's one of those Backlight "Gaming" monsters. And everyone seems to hate the volume dial, rather than those awful volume buttons. I can't think of any others with hotkey functionality off the top of my head, perhaps the X4, but that's basically just a bog-standard Keyboard that microsoft makes people pay extra for.
Hey, I have the MS x6 too and its rather nice. I would say that you should have a look at the x4. It has all that you mentioned but it also has anti ghostings, macros and the keys light up which is really handy. Also amazon has them on at about £30!
I've got a G15 V2 im selling for £45 posted, I loved it when I used it, never had any complaints with it, and more and more games are supporting the screen! Also really useful when listening to music etc.
Spend a bit more, say 60 quid, and get a mechanical keyboard. When that still lasts after 20 years you'll have saved more than one keyboard.
you can get a rather nice mechanical cherry brand keyboard in the £40ish range. their cheapest mechanical, the cherry classic (g80-3000) is fairly basic and has no multimedia keys, but is built very well. thier membrane keyboards are made well too if that budget is too high for you. take a look at the cherry infinity. if you don't mind low profile keycaps it may be a good fit. you can find these in the £20ish range.