I also got bored with the default omnia interface and have now upgraded to a custom windows mobile 6.5 rom with Manilla2D installed(the usual HTC interface), its so much easier to use, the HTC interface pretty much completly replaces the windows mobile one(which is still pretty bad even with wm6.5!)

Checkout i900 / General Omnia ROM Discussion - WinMo @ MoDaCo

You should have taken advantage of the whole orange changing their terms thing - I got out of my orange contract and moved onto a T-Mobile Sim only deal and kept the omnia(after unlocking it ) My wife refuses to let me get a new phone just yet lol