New PC
I have loaded and played my casinos on my other PC at my Mum's house. It is using a different ISP, and is obviously a different machine. I had no problems with this. Cryptologic will prompt you to open a new account (no info stored in registry), however look carefully, and there is an option to register an existing account to a new machine. You will be asked for all the usual login info, but in addition will have to supply the account number.
Microgaming will open the new account registration screen, but this has an option to use an existing account.
The fancy download managers of some casinos will assume you are a new player, and you must be careful NOT to create a new account. With Microgaming, select "register later" and just let the download manager install the casino.
With a small number of casinos, it may be necessary to contact support to activate an existing account on a new machine.
Neteller will notice changes in access, and it would be best to let them know. I had this trouble when I checked my balances from my Mum's house, and I had to get them to register the fact that access from there was valid so as not to have the security systems block the account login.