You have a choice of ways of doing this.
1 Buy an adsl wireless modem and ethernet cable (about £60) and connect both pcs through this
2 Buy a PCI or USB wireless adapter (about £20) for your pc and connect to the laptop wirelessly
Option 1 allows the two pcs to operate independently but is more expensive; option 2 requires your pc to be on all the time to let the laptop connect to the internet.
In some respects option 1 is easier to set up, easier to maintain and more secure. You can retain your bt voyager 1010 for either option, though if file transfers are a major consideration you may want to buy a faster one (another £20).
Set-up of either option is relatively straight-forward, but rather than go through both now, it would be useful to get an idea of which route you would like to follow.