upgrading ram on imac 5,1

I will be upgrading from my current ram of 1gb to 3b soon. I was looking at crucial ram but my question is can i just buy the 2gb to make a total of 3gb on my imac or do i need to buy the 1gb from crucial also? I guess I am wondering if they need to match each other or not because my current 1gb of ram is the one the imac came with but it just isnt enough anymore to many wheels of death!

Crucial has a useful tool at Memory upgrades from Crucial.com - Crucial Mac System Scanner that will scan your Mac and tell you what the possible combinations are to reach your goal total memory..

Regards

Yeah i used it and it wouldnt work. I know i have the right memory as far as specs go, just dont know if i should get just the 2gb and add to my current 1gb or get both the 1gb and 2gb from crucial and replace the whole thing. will 2gb crucial work proficiently with the 1gb apple ram is my question i guess

You should grab whatever RAM is specified for your Mac, you can grab just the 2GB stick and get a total of 3GB without having to replace the stock Apple memory..

Regards

Since a 1GB and a 2GB won't be a matched pair anyway, Go for it. Should work fine.