I am not with Tiscali but had a look at their website. You will need to download drivers to make your modem compatible with Vista - read and download here:
http://uk-tiscali.custhelp.com/cgi-bin/uk_tisc ali.cfg/php/enduser/std_adp.php?p_faqid=517
You should be able to plug your pc straight in to the ethernet after you have done that.
I don't use Outlook, so I'll pass on that.
Your new pc will have an ethernet socket already so no need to worry about that.
LAN is Local Area Network - when two or more computers connect to the same internet connection, usually by router. Unless you want to be wireless, don't worry about it.
My firewire socket is a teeny tiny thing that my camera connects to. I never use it - it is quicker to put the memory card from the camera into the memory card reader.
Bluetooth allows you to use wireless bluetooth headphones with your pc; or connect your mobile phone to the pc without wires to transfer data - other other pcs such as laptops or hand held; or blue tooth mouse and so on.