It's nothing to be overly worried about at all.
* The LGA775 CPUs themselves have the top heatspreader to protect the chip, and they're also pinless.
* The pins on the motherboard, as others have mentioned, are extremely short. The retaining bracket/socket cover protects it futher.
* The socket itself is keyed, and there's a plastic border all the way around it that's higher than the height of the pins. So the CPU is not going to touch the pins unless it's oriented in the correct direction.
* You just drop the CPU onto the socket, no pushing/force is required.
* After you install the CPU, you swing the retaining bracket cover onto the CPU and the motherboard socket. It's not going to shift or move unless you explicitly unlock the bracket.
No comment as far as the heatsink. I've never used a stock LGA775 heatsink. I will say this though -- the heatsink weight limit that Intel set down for LGA775 is technically 450g. But I've never had an issue using a heatsink that weighs twice that max weight on either of my LGA775 boards (plus there's also that additional force from pushing down onto the heatsink to install it).
- They're really not that easy to break or damage.