Yup, no problem. That's the good thing about WiFi or the IEEE's 802.11 standards.
Here is the only thing you need to consider: What format of 802.11 will you be using. If you're going to get a new PowerBook you'll probably have AirPort Extreme, which operates as 802.11g (up to 54Mbps at 2.4GHz and backwards compatible with 802.11b). So, you could get a Linksys 802.11g router for maximum speed or a slower but cheaper 802.11b router (up to 11Mbps @ 2.4GHz). If you get a unit with the standard AirPort (shipping in 2002 or a PowerBook 15"), that's 802.11b, so you could get the 802.11b router or an 802.11g router, but it won't be any faster using the g unit.
DO NOT GET AN 802.11a ROUTER. It operates at 5.8GHz to get up to 54Mbps, but will not work with 802.11g or 802.11b at the lower 2.4GHz.