Pretty much hard to go wrong with anything available at the moment.
Something like this:
http://www.memoryexpress.com/Product...21221(ME).aspx
and any new laptop are going to play nice with each other.
Even a $500 laptop by now should have wifi on it. I doubt anything new will not have this option, but just check what 802.11 level they have. 802.11g is faster than 802.11b and 802.11n is even faster but just be wary that the 802.11n standard is still in draft form (last time I checked anyhow) and may in fact still change (although I doubt it). Which just means if it DOES change any device that claims "802.11n compliant" may need a firmware update down the road (not really a big deal though).
More reading on the standards here:
http://en.wikipedia.org/wiki/IEEE_802.11
For security there's WEP, and WPA and WPA2. WEP encryption was cracked eons ago so don't bother but WPA2 should still be OK I think. Unless you're OK with giving your neighbours free internet access (although there are incidents of creeps though who drive around looking for unsecured wifi points to download kiddie porn and so on so it just makes sense to lock your network down anyhow). Basically you just get a network access key password generated and you have to enter it anytime you have a new device you want to connect to your network. No biggie.
Fun stuff though, you'll love having wifi in your house.
