Herp,
Definitely investigate before buying!
Get the module out, note down as much info as you can, also check how many RAM slots you have in total / free.
If you still have the manual see if that has anything about upgrading.
There are a couple of useful websites for matching RAM:
http://www.kingston.com/ukroot/
http://www.crucial.com/uk/
Crucial even has a facility to check the RAM fitted and give you an online report!
Also try searching the Web for your Time computer model - although with Time going t*ts-up, there may not be much help.