WRT54G Firmware/Splash Page Question

Hi all, just after some advice please!

I run a shop/cafe where the customers can get on the internet thanks to our free wifi. We use a Linksys WRT54G (version 2 i think). From searching the forums i have realised there are firmware upgrades available that would allow us to show a spalsh page to our customers...

Ok, what I would like to do is be able to create my own spash page where i could give the customers the choice to answer a few questions about the store and save the information they enter to a file.

Firstly is there any firmware that would allow me to do this?
And if so how would i save the information the customers enter in my questionaire splash page? presumably i would save the info to my pc out back which is hardwired to my WRT54G?? im just not sure!!

hope i have made my question clear, please forgive my if my terminology is wrong but im quite new to al this!!

thanks for your help