Can a socket LGA775 run Windows 7 comfortably

Solution
Yes my core2duo e8400 and e7300 ran windows 7 just fine. Both with 4gb and 8gb of ram, though obviously with 8gb multitasking was much smoother.
Core 2 processors have no problem with Windows 7/8 or 10.

Even core 2 duo processors have no problem with running windows smoothly. You do need atleast 2GB's of RAM and preferably 4GB or more.

Core 2 quad processors even allow for some gaming, League of legends, WoW, Far cry 3 and the need for speed series.

If you are not going to do any heavy tasks on it however, you should be just fine. But games that i listed above are all playable along with a decent graphics card.