I'm Sure Sandra will delight in explaining the merits of a Broadband Router, GSS, and why every home should have one!
It basically means you can connect two PCs (or a PC and a laptop) to the same phone line, as far as I understand it. That's as far as my knowledge goes, as I only have one PC, so I don't need a router.
As for Freeserve, are you not tied into a minimum term contract with them? Changing your broadband supplier is not as simple as changing a 56K Dial Up ISP, as there are usually set up costs to consider. Would it not be better to sort out the problems you are having with Freeserve, rather than changing?