Yeah. Cat6 is just a waste of effort/money over Cat5e for gig-ethernet. Either will perform exactly the same, at a full gigabit speed up to 100m distance between hubs/repeaters.

For older Cat5 (not Cat5e), the maximum distance for gigabit will be less (I forget, but something like 30m instead of 100m).

Note that I have actually run 100mbit/sec ethernet over Cat3 telephone wiring, but only for about 50 feet of distance. The shorter the distance, the more forgiving ethernet becomes of cable quality.

If you're trying to use 2.5gigabit or faster, then Cat6 becomes useful.

EDIT: Note that this may depend somewhat on the cable quality despite the cat5 or cat5e designation on the sheathing. The cat5e stuff I use here claims 350Mhz bandwidth, which is better than a lot of cat6 stuff (and not the same thing as the bits/sec speed ratings),