Tranferring Cubase 6 from PC to Mac


I’m looking to transfer Cubase 6 and all my recordings from a PC to an iMac.

I’ve bought the iMac second hand and I need to increase the RAM from 4 meg to 8 meg, does anyone have any sites I can buy the extra Meg.

Could someone point me in the right direction please and let me know the process involved !

Thanks for any help in advance