Broadband: Do I need a crossover ethernet cable?

Do I need a crossover ethernet cable?

Hi, so I'm taking intro to networking at a community college and my teacher said that if you go router to router, switch to switch, pc to pc etc with an ethernet cable that it needs to be a crossover rather then a straight cable.

So right now my pc is in my room and the router is clear on the other side of the house, I have a 100 foot straight ethernet cable going from the router under the house and up to my computer.

I will be buying a netbook pretty soon so I can take notes in class and just have access to a computer when I don't want to be sitting in my room. The router downstairs is a Linksys wrt54g and the signal upstairs is pretty weak and I'm wanting something stronger.

I was thinking about getting another router (and if I do get another one will it need to be the same one? linksys wrt54g) and putting it in my room for a stronger connection. Since I found out that if you do do router to router you need a crossover ethernet does that mean it would not work if I did that since it is a straight ethernet cable? If I need to I can borrow some RJ-45 crimpers from my teacher and make it a crossover but is that really necessary? Or will it just work as it is? Thanks a bunch