Cat5e is sufficient, it is certainly OK for the job and more resistant to crosstalk than standard Cat5. Cat6, as you probably surmised through your web searches, is 100% certified for Gigabit and less likely to encounter crosstalk and other RF interference from sources such as power lines, etc. As long as all else is gigabit (routers, switches, NICs) then you should be fine. When stringing your network, try to resist the temptation to follow paths of your power lines and, whenever possible, if you have to cross a power line, do so perpendicular to the direction the power line is running to minimize any RF interference from it. This is what is done when wiring remote speakers for home theater systems and is recommended for PC networks as well.