[Maced] Are all RAM chips the same

[kel at edugator.net.au]

Having upgraded my home iMac 1.8 GHz PowerPC G5 to Leopard I thought  
it wise to upgrade my RAM as well. Currently has 1GB - two 512 chips.  
I've been told these have to be discarded and I need to instal two 1GB  
chips if I want 2GB total RAM.

Apparently I need PC3200 RAM chips.

Local Apple store wants $245 for a 1 GB chip.

Shopbot search reveals 20 stores selling PC3200 chips from $46 - $60

ePowerMac website lists 1Gb Mac chips for my model for $136.

As you can see there are big price differences.

Are the cheaper chips good enough or should I stick to buying from a  
Mac store?

Thanks

Kel