Dear Keab
This must be terribly distressing for you! I think there are several options open to you.
1/ Bug her to buy you your own computer! have you seen the advert "mummy can i have a rabbit?"
2/ Save up and buy your own computer
3/ Check out the library and any cyber cafes
4/ Campaign local council for cyber cafes if necessary
5/ Introduce her to a new hobby
6/ Invite her friends and or neighbours over and then jump on the computer
7/ When she's asleep get some packing tape and tie her up so she can't get to the computer.........do remember to pass her food and water though
8/ Previous suggestion...spike her drinks and when she's out cold hey presto the computers all yours
Hope this helps
Sin