|Shouldn't you have asked that question before you got a D600?|
IMHO, they're not horrible. I have a 7 yr old D600, it wasn't a bad machine. Mine is on its last legs though. Mine had issue with not working on a dock, an LCD screen hinge broke, the power switch post is cracked (needs to be resoldered on the motherboard), the BroadCom onboard NIC doesn't work, and now the WiFi adapter sometimes cuts out and isn't seen by the system. But, other than all that, it still powers up & works 96% of the time (haha). They don't last forever.
I have an even older, slower Latitude D400 that works just fine...although it didn't see the regular use & travel like the D600 did. I also have some older C610's that work OK still. And, in my "working junk pile", I have some even older & slower Latitude CPx laptops (650-750 Mhz CPUs) that used to run Windows 98 & 2000 OK. They still run, but they're too heavy & slow to really want to use.
MOOOOooove! OH and you're welcome!