Add some RAM, it's cheap these days. I'd go to -at least- 2gb. 4gb would be better, IF your friend is planning on keeping the iMac another year or two.
Also, check to see how "filled" the hard drive is. You should have about 10% of the total capacity always "open", for this is used by the invisible swap files, etc.
Also, after 5 years, I'll bet the drive is SERIOUSLY fragmented. There are defragmenters that can clean this up, but they're all "pay for".
A cheap way to clean up the drive is:
1. Use CarbonCopyCloner to "dupe" the contents to an empty drive or backup partition (your friend has a backup, right?), then
2. Boot from the backup clone, and re-initialize the internal drive (yes, clean it right off)
3. Next, RE-CLONE the contents of the backup back to the internal. The files will all be copied contiguously, and automatically de-fragmented.
It wouldn't hurt to repair permissions as well.
You might try downloading the free "MacJanitor" and running all the tasks.