Thats ok. I was joking about the 1 year later, just made me laugh that its almost 1 year to the day this thread was last replied to.
By setting your Access point to outside the dhcp scope it means there is no risk of any other device being issued the same IP address and causing a conflict.
So long as you have router 192.168.x.1 and access point 192.168.x.2, with your dhcp scope being 192.168.x.100 > 200 then you should be fine.
Set the SSID to match your router, and same password and security (WEP/WPA/WPA2).
Also you may consider putting them on to different channels, but let's look at that once you are setup with the access point first.
There are devices which use the internal power lines of buildings to extend networks. These work in most situations, but personally I would not recommend them when you have CAT5 in place. That said you need the new access point to be in the area of weak signal to get the best effect from it.