For that price you aint gonna get anything capable of kicking out 5.1 DD. Sometimes you will find some crap cheapos at argos that claim to be good but they aren't so don't waste your cash.
There is very very little 5.1 on the V+ so wouldn't worry about that.
The best thing you can do is find a DVD/Home cinema system that delivers 5.1 from DVDs and connect your TV to that.
You will not get 5.1 from your external kit but it will make them sound 100x better than the crap speakers flat panel tv's have inside them.
It just so happens that i have such a system for sale! fancy that. It will shake your house down! A very good system with 5.1 on DVD and pro logicII on other sources.
the down side is that £50 is still a little short. I paid £200 for this and i am looking for £90 plus postage. It is 8 months old.