Q: can i get additional memory

What model iMac do you have? With only 1GB of memory you are a worthy candidate for adding more.

To find out how much memory your iMac supports you can check sites like this:

http://support.apple.com/kb/HT3011

http://www.crucial.com

Yes, but how much you can add would depend upon the actual model you own which you did not detail sufficiently. Open System Profiler in the Utilities folder and note the Model Identifier that is displayed then post it here so we can give you more information.

You can install a maximum of 2 - 200-pin PC2-5300 (667MHz) DDR2 SO-DIMMs 2 GBs each for a total of 4 GBs installed. However, in your model only 3 GBs will be available to the user.

You appear to have one of the iMac 24-inch systems released in September 2006. Here are two Apple articles that provides additional information about memory for your system.

http://support.apple.com/kb/HT1432

http://support.apple.com/kb/HT2821

I recommend two sources: OWC and DataMem

Any suggestions on where/who to purchase from?

You may get more answers if you include your geographic location in your profile.

The links Kappy provides are both in the US. OWC ships to a number of international destinations but may not include you location. Data Memory Systems is more limited in international shipping.