Odds are you need a new reicever, esp. if you want surround sound. You can get switches and the like at RadioShack I believe, but it's only really a temporary solution.
If you really want to go 'cheap', you could get a DVD/VCR/Reciever combo at somewhere like Best Buy or (ick) Wal-Mart (or don't go there

). It has room for a CD play and a Casseste player for ports. But if you need to overhaul it in the future, you can't replace the individual components, you have to replace the whole freakin thing at once.