yeah a pc would be a good way to go, you can get a good spec for making music on for about 5-600 quid, bung reason on it and bobs your uncle ;) , theres lot of help on production and software etc on the net and a lot of helpful people on forums (like this one) that are allways happy to help.

but in regards to your setup a pc and a copy of reason would be all you needed to start getting into production ;)