Question : Problem: Can I install a Intel Core-Duo 2 45nm on a P5LD2 Rev 2.0(intel 945p chipset)?

I have an old Asus P5LD2 REV 2.0 (intel 945p chipset) and i will be updating to the latest bios but i was wondering if it takes 45nm core-duo 2 at any speed.  I think on the box it said 65nm and future 45nm.  Will there be voltage issues because the die is smaller or something.

Answer : Problem: Can I install a Intel Core-Duo 2 45nm on a P5LD2 Rev 2.0(intel 945p chipset)?

As jamietoner noted, none of the 45nm CPU's will work; nor will any quad cores. In fact, very few of the supported Core architecture CPUs are still available ... so your best source is probably ebay. Here's an E6600 that would work nicely (Note the auction closes in ~ 5 hours):

http://cgi.ebay.com/Intel-E6600-Core-2-Duo-CPU-retail_W0QQitemZ170286761523QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item170286761523&_trksid=p3286.c0.m14&_trkparms=72%3A1205%7C66%3A3%7C65%3A12%7C39%3A2%7C240%3A1318