If you are installing from the blue disc, you shouldn't have any problems.
But remember to right-click the install program and "Run As Administrator".
If you are installing from an older Black and White disc, there are a few extra steps to follow.
...
Re: Reusing PGC & PGD pins
Yes you can reuse them but you need to be careful as to what circuitry you hang off the pins.
tumbleweed Today, 13:29Most ICSP programmers have 4.7K pull-down resistors on the PGC/PGD pins and assume the pins will idle...