If you are having the same problem as me in getting the WPA-PSK wi-fi connectivity set up between a Netgear Router and an XP machine, here's a work around I've found after hours of searching:
If you just assign your xp machine it's own IP and set the default gateway to that of the router it should bypass the step where the machine is unable to acquire a new IP address from the router.
So right click your wireless connection in network places, go to status, then properties.Scroll down to TCP/IP, goto properties on that.
Next screen check 'User the following IP address' Pick one that your router allows or has been setup for on DHCP.
In my case this was xx.yy.0.3, subnet mask should take care of its self. Set the Default gateway to your router's ip, In my case xx.yy.0.1.
For DNS set the preferred DNS server as the router's ip, e.g. again in my case xx.yy.0.1.
Now try connecting to the router with WPA/PSK running, enter your pass key in carefully and it should work.
This is by no means a nice or clean fix but it got my wireless up and running!!