Run an extension cable from the phone socket nearest to the room that your PC will be in.
I use this set up. The extension plugs in to the nearest phone socket. You then plug the phone back into the socket on that end of the extension.
My extension cable then runs for about 25 feet to where my PC is.
The only DIY part was screwing the socket next to the PC into the wall and wiring the end of the extension cable into that socket (4 wires if I remember correctly).
To tidy the whole thing up the cable is clipped along the skirting board and around a door frame.
Try Dixons, Currys, PC World etc.