GigE Network Tap - Confused

HELP
I need to setup a network tap on a GigE RJ45 connection. Everything I am seeing is a 4 port device (tap) that requires a dual port nic in order to see all the packets. Well, what I have done in the past is just setup port mirroring or slip in a dual speed HUB and use my laptop with wireshark and get the info I need - done. But now that I need to do this with a GigE link it appears that either I have been doing something wrong and or I need to do it differently now. I guess my question is, can I find a network tap that supports GigE and still just use my laptop along with one RJ45 connection and wireshark to get the job done??
Thanks for any help, JJ