..i've been with them since ADSL first came out and they're excellent.
You have a few choices, not sure if you want wireless networking or wired networking?
Basically, you'll need some mechanism for connecting the 2 other PCs to yours. The easiest (in terms of hassle with cabling etc. around the house - especially if they're not all in the same room) might be to go wireless.
Pipex won't necessarily know/care about your home networking arrangement, but it certainly should work and does for me.
So, to get the other 2 PCs connected to the internet as well, you could get PCI Wireless cards for them both, and for your existing one, and do "internet connection sharing".
I would however recommend getting a Wireless ADSL router, and then assuming your currently connected PC is near to the router, connect that over a wired-connection (i'm assuming it has a network card in it already) to the router, and the other 2 PCs with PCI cards.
There's loads of models out there, but I must admit though I'm familiar with the concepts I haven't actually done it. Draytek seem very good and i've used their wired ADSL router, but not their wireless.
You may want to get all from the same provider e.g. Netgear are also good in my experience. I can recommend: click here
who will be able to help you if you explain to them what you are trying to do.