In no particular order..... Good, solid board. I've got one of its bretheren in my MCe2k5 server (specifically, a GA-965-DS3, which you might want to take a look at.) One thing to keep in mind, should you go with the P35, is the lack of onboard video - you'll need to install (at least temporarily) a PCIe or PCI vidcard to run setup. The 965, at least, has onboard (and, good, at that.) Plus, it costs less. 
Onboard eSATA, or lack thereof, I wouldn't call a deal-breaker. If you really find yourself needing more SATA ports (either internal or external), you can always add a SATA controller card later, for little cost.
As for the NIC: it's getting harder and harder to find boards that don't have a gigabit port. However, a gigabit NIC doesn't mean that you'll need a gigabit switch just yet: the NIC will only run as fast at what it's connected to. Connect a gigabit NIC to a 10/100 switch, and it'll run at 100Mb/s. But, it (the 1Gb potential) will be there, waiting, should you ever find the need to upgrade your network.
My advice would be to go with the 965. Great board, nice price.
Find yourself a case yet?