What do I need to upgrade my PC in preparation for Broadband?
Nothing - virtually every PC in current everyday use is more than capable of connecting to broadband.
If you have a free USB socket (it doesn’t have to be USB2) then you can connect to ADSL Broadband (ordinary phone line).
If you have a free USB or Network socket you can connect to Virgin Media Cable Broadband (previously NTL or Telewest).
Only a network socket and want to connect to ADSL? You can connect through an ADSL modem router.
If your PC doesn’t have any USB or network sockets then it’s probably very old, but could connect by the addition of a network card or a USB card or a Wireless card.
Broadband speed may be fast compared to dial-up internet speed, but compared to the internal speed of a PC it is trivial...