Wheel upgrade

[busman]

As some of you may have read in earlier threads that I have a problem with my rear axle.
A very kind friend has given me a reason wheel with a 10 speed cassette on.
My question is how easy is it to upgrade the gear shifter and chain.
At present I'm using my chain that was already on the bike and shifter

 

[Citius]

Why not just change the cassette?

 

[busman]

My old cassette is a 7 speed screw on

 

[cyberknight]

Buy a 7 speed cassette , new chain and i believe you will need a spacer on the hub before you put the cassette on , i have read a 4 mm one will do it but ask your LBS.
A lot cheaper than shifters, chain, cassette + new rear deraillier.which is what gonna set you back £200 +

 

[lpretro1]

If it is a screw on it ain't a cassette - it's a freewheel