Don't have Tiscali but I suspect the principle will be the same.

Download or save your e-mail and the attachments.
Locate the file(s) where these downloads have been saved.
They may be saved as downloads under your name, or text files etc.
Right click on the file name and an Option Box should hopefully open. One of the options should be "Send to" - and one of the destinations should be the Memory Stick. Left click on this and follow the instructions.

Give this a try and see if it works on your system.