Connecting Ipads to my PC via wireless link

[#1]

I have a Dell GX270 with XP Pro, and a Netgear Wireless Router. My grandchildren visited today with an Ipad. I tried to get it to link to the web via wireless to my Router. My PC can look at the Netgear data and see the Ipad MAC Address, so I have added that to my Netgear permitted access list. The Ipad says it can see my network (it names it correctly), but when I try to connect it, the Ipad asks for a password. I've tried every password I can think of (not many). My grandchildren say the Ipad hasn't got a password.
If anyone can suggest where I might find the password the Ipad is asking for, I would be grateful
Thanks

[#2]

written on the bottom of thr router 
unless youve changed  ;)it

[#3]

@penneck:- Have a look at
-dn0

[#4]

use the password for router - my iPad connects with that

[#5]

Thanks. Problem solved.
I had tried the password on the bottom of the router, and I had tried the encryption key (just in case). The solution appears to have been that I hadn't loaded the Ipad MAC Address onto my router before I tried the various passwords, and I didn't go back to try the IPad after I had added the MAC Address. Now that the router has the MAC Address, it allows me to connect from the Ipad to the web.
It seems that the order of actions in which you set the link up has to be done a bit at a time at each end, going back and forth until it is done.
Thanks to "journeys" and "PeterLoftus" (and "jmdlp" whose reply came in as I was typing this)

[#6]

Glad it got connected but I did not have to input MAC at all - mine just connected.
when I took it to a friends house again all I had to do was input the router password.

[#7]

Maybe you should give up on MAC address filtering and return to the default setting of 'Off''?  Those in the know about wireless security say it offers little challenge to a determined hacker and yet it defeated you for some time.