Cyclocross - Looking for some advice on my drivetrain.

So I just bought a second hand cross bike from ebay. As far as I know it was built up by the previous owner as a commuter bike for around London, using mainly campy bits.

http://i.imgur.com/Ev52n.jpg (http://imgur.com/Ev52n)

I've already spent a lot of money on new cables, outers, tyres, bars, tape, stem and seatpost, and was hoping to spend a little more on some Hudz and smaller chainrings soon.

Problem is I snapped my chain on saturday, added a quicklink to fix it, went out again on Sunday and it snapped again but on a different link. The chain is a shimano HG-53 chain I think and looking at it closely there are quite a few different branded links, which makes me think it has been repaired a lot.

So I need a new chain - and in theory I need a new cassette really (although the seller did say the cassette wasn't that old, but I'm not sure how long this chain had been used for) - I've been looking at cheaper Campagnolo compatible cassettes and chains like mavic chains (http://www.chainreactioncycles.com/Models.aspx?ModelID=33382) etc. And I'm gonna need to get a campy cassette tool as well.

Another problem I have is that I have Campagnolo cranks with 39-53, and from what Sheldon Brown tells me I can't have a smaller ring than a 39t on campy cranks - I wanted to end up with something like 34/36-48.

So as well as buying the new cassette and chain, do you think I will need to get a whole new chainset (cranks bb etc?) in order to get smaller rings up front?

It's annoying because I was really enjoying the bike, especially the break from road cycling, but now it is just sitting in my hall out of action unless I sink a good amount of money into it. Maybe just go single up front? Leave the front rings as they are for now?

Meh please advise! What do you think my cheapest option is? Should I replace the cassette as well as my chain?

Ribblecycles.co.uk is your friend...you can buy compact campy along with mitche casettes and centaur chains etc. If your looking for permission to buy a group, be my guest. Chain, cassette, $45 crank couple of hundred from campy. truvativ elita $80 w/bb $125 all told.

Why should you replace your cassette in theory? If your cassette is not badly worn, then I would say keep it and just purchase a new chain. If the teeth on your cassette look out of shape/worn, then get a new cassette as well.
Hope this helps: http://bicycletutor.com/chain-wear/

Ribblecycles.co.uk is your friend...you can buy compact campy along with mitche casettes and centaur chains etc. If your looking for permission to buy a group, be my guest. Chain, cassette, $45 crank couple of hundred from campy. truvativ elita $80 w/bb $125 all told.

+1 on leaving the cassette alone unless it skips with a new chain. It's probably fine. You get a bunch of cassettes out of each chain.

Campagnolo Veloce cassettes use the same nickel-plated cogs as Record and cost less than Miche. There's no reason to buy anything else unless you're a weight weenie trading money for grams.

Centaur: The largest pair of sprockets are on an aluminum carrier.
Chorus/Record: The largest 2 (11-21/11-23) or 3 (all others) pairs are on aluminum carriers.
Record: The largest cogs are titanium.

Campy cranks are 135bcd; there's no way anything smaller than 39 will fit on there. Even on 130bcd, the smallest readily available ring is a 38; there's also a 37 in the works. To get rings smaller than that, one needs a compact crank, 110bcd.

Thanks for the replies - I know my post was a bit vague.

I've decided to keep the cassette as it really isn't that worn, but I bought a mavic chain cheap online and won a 110bcd FSA gossamer crankset for about £30 on ebay. Just need a BB and then I'm done!