There is NP installing EQ on any machine you own. At this point you can use either machine to play EQ. BUT, be aware that the .ini, .log and some of the .txt files are used for customiztation are held "client side", so these will have to be copied to the new machine. Make sure you install all your expansions so that when you log on you will have access to them.
You will NOT be able to play 1 account from both machines at the same time. So, if your main and "significant others" main are on one account you are SOOL. Infact technically yur not supposed to share accounts.
For a small fee ($50?) SOE will transfer one main to another account, and will charge you a monthy fee.
Gordon