Should i get all season tires, or winter tires? I have the Nitto NT555 w/ 18's on it right now but i dont know which to put for winter. And im going to put the stock 16" rims. So what do you think is better?

Go here:

http://www.driveaccord.net/forums/showthread.php?t=23212

Here is another thread that I would recommend reading. It talks about 19", but would be applicable in your case too.

http://www.driveaccord.net/forums/showthread.php?t=23127

Should i get all season tires, or winter tires? I have the Nitto NT555 w/ 18's on it right now but i dont know which to put for winter. And im going to put the stock 16" rims. So what do you think is better?

Simple, if you will be driving on ice and snow, get proper winter tires. Depending on when you bought your new all-seasons, they "may" be okay for 1 winter depending on your climate, but you really should go with true winter. They are a much softer rubber compound that will stick to the ice and carve into the snow with the sipes (cut pattern) of the tread and soft rubber sticks to the ice.

Think hockey, players play with a frozen puck b/c it glides along the ice better than a soft rubber one does, your all season tires would freeze up and glide along the ice, but your winter softer rubber would provide more grip/traction.

They will cost, yes, but probably less than sliding into someones bumper at an intersection that has been turned into an ice slide :)