That's pretty tight for a home network.
I've seen the same problem as you; not all PCs seem to support WPA2 properly, especially earlier Dell laptops. The option is there, you can select it and apparently use it but if you do the wireless connection keeps dropping in and out. Choose WPA instead and it's rock-solid all the time
I use static IP addresses at home but I don't use the usual 192.168.0.0/24 or 192.168.1.0/24 range. I've configured a completely "odd range", something like 10.14.173.0/26. If I have friends who bring a laptop, I tell them which IP address, SNM, DG and DNS to use and add them to the allowed MAC addresses.
Maybe I'm paranoid, but I don't want to make it easy for someone to just latch onto my wireless. I know that it's possible if they're sufficiently skilled and determined but, as there are lots of other wireless networks out there, they're likely to move to a softer target.
I've got a question though, do you also make use of static ip addresses instead of dynamic ones?
We have DHCP running in our building, but I personally use a static IP, not for security, but simply because the initial association to the AP becomes much faster since it skips the part where it queries the DHCP.
For WPA, as far as I know, the main deference between WPA and WPA2 is that the later supports the full 802.11i features along with CCMP encryption. WPA uses only TKIP encryption. But practically, like TheBishop said for a home network, WPA should be fine. I use it at my home. The one thing I would stress on though is to use a LONG passphrase for your WPA, 13 or more characters should be good. Long passphrases make brute-force attacks much harder.