Memory upgrade config questions for a 2008 iMac

I've got an early 2008 iMac with 2GB memory (1+1), and want to upgrade it, as I'm having a few issues running iPhoto and iMovie, plus a few other things, well. My target was 4GB of memory, as 6GB gets a bit expensive for an aging computer.

So, my options are:

(all are PC6400 DDR2 800MHz)

1) Replace memory with 2GB + 2GB (~$60)
2) Replace memory with one 4GB (~$70)
3) Replace one 1GB memory module with a 4GB module, leaving 4GB +1GB. (~$70)

What would be my best choice? In particular, does option #3 have any issues -- would it be better than option #2?

GGJstudios said:

There is a slight performance benefit in using matched pairs of RAM, such as 2x2GB.
MR Guide to Matched RAM on Intel Macs

Click to expand...

Thanks, I understand that.

But that doesn't mean that the 2GB x 2GB config would be better than the single module 4GB config would it?

And if it's not, and I do get the single 4GB module, does adding the 1GB module to the second slot actually slow down the 4GM module?