iMac 21.5' RAM Upgrade Question.

Hello,
I currently have a iMac (late 2009) 21.5' model with a Intel Core 2 Duo running at 3.06ghz.
This is currently running on 4gb's of RAM and I had a couple of questions about upgrading, not about how to do it, more the spec side.
1. Do you need (or would you recommend) to use matching RAM? As the iMac has 2x 2GB's I could simply replace one to a 4gb RAM card giving the machine 6GB's RAM? Could I experience any problems with this?
2. With the current processor will it really benefit an upgrade from 4gb to 6 or 8? Will it still be able to handle/ get the full use of 8GB's of ram, or is that more than the processor can handle?
3. Will more RAM speed up video editing and exporting?

Thanks a lot guys, have a good day

*Love the look of the forum too*

Craig

i upgraded the same one you have today to 8GB, from the RAM i had in my MBP. i dont notice a huge amount of difference, but i can do alot more stuff at the same time, especially with logic. i have 4 x 2GB sticks. ive heard its better to use matching RAM but you dont have to.

boosting it will help with video editing as you are using lots of files, not sure on the exporting.

Would it be ok to have a 4gb stick and a 1gb stick in the computer?

Apple - Support - Discussions - Mixing RAM Speeds ...

i dont think you'd see much of a performance increase, adding a 1gb stick.

at the moment i have 2 x 1GB if i take out a 1gb stick and put in a 4GB.

i swapped the ram with my mac mini