No matter what you do ... you will lose.
LGA 775 replaces 478 pin which replaced 423 pin which replaced socket 370 which replaced slot 1 which replaced... it goes on.
The only thing that's guaranteed is that one of the main reasons you are going 775 (925/915 chipsets) is future-protection, but that is not a good reason. Sure, you have PCI Express, DDRII etc. But in a few months BTX will take over from ATX. Cases, PSUs etc will all move over. Intel will change the number of pins in their CPUs, DDRII may be replaced by the new RDRAM, TCQ (new, improved flavour SATA) advantages will be overtaken by a better technology, etc. And you'll be stuck.
If you can't be dissuaded Asus have some good 925 boards and Asus are usually a good bet for quality products. But, if you are practical, you'll look at all the 775s and settle for a 478. Otherwise you'll join the legion of people who amaze me with their eagerness to be guinea pigs ;)
Almost all 925 chipset boards today have gigabit LAN.