In the forst instance I'd advise you to Browse the World Of Windows Netwoking (WOWN) site click here
It's a very German (plain) site, but is full of FAQs and advice for networking all types of OS's and PCs.
Then work out a budget and see what you can afford to do vs what is best for the property and ISP connection.
Some ISPs don't care if you network (Telewest don't) Some do. You may have to lie to your supplier !
Also, You can probably only have one subscriber, make it the most reliable in the house, and (s)he will then have to allocate secondary emails to the other housemates if you all want ISP mail.
Alternatively, do as I did. Buy a Domain and get someone to host is for you. That is much cheaper than having an ISP - about £50.00pa or £1.00 per week. This will then give you your own email which is yours for as long as you won the domain and pay the host. You will still have to set the OUTGOING mail to be the same as the main subscriber, but you set your in-coming mail deatils as proviede by the host you choose for your domain.
NEVER EVER BUY A DOMAIN FROM A UK COMPANY. Get it in the US, even .co.uk are much cheaper there. Steve, My flatmate bought his sister one for $25.00 for 2 years. Mine cost $150.00 for 10 years and is a .com from Verisign. Clara.net wanted £45.00 for 2 years for the same domain!
RIP OFF UK STRIKES AGAIN.