Welcome page with language choices?

I am thinking I want to have a welcome page with say a logo and language choice. I can make that easily enough but, my question is:

I want the welcome page only to appear to new visitors. (ie. it should remember their language choice and go directly to the main page the second time they come to the store)

I am pretty sure I have to do this with asp.net but I really have no idea what I am doing. Can anyone point me in the right direction?

also I own 4 of the same domain name with different extentions: The .net is the main site, while the others are just going to be directing to it. The .com and .ca sites are going to be the main sites that are advertised so I figured I would direct them to the .net from these sites welcome page.

Zen Cart has a language sidebox selector and if memory serves my right it recalls a users preference upon login

hmm ok i'm more trying to solve this issue i'm having with the .com being on a different server and i cannot move it. Instead of forwarding the adress to my .net site right away, I want to have a welcome page - and once they have visited that page i want it to forward to the .net site.. do you think i should get someone to write me some code for this or am i way off?

Your other domains witha static page with little content and what is there is static will not rank well at all if this is a concern