5Ghz Wifi antennas?

I have a PCI wifi card with two antenna sockets, I currently have two different antennas attached which is probably not ideal. The wifi card is an edimax 7727In.

I am connecting to a virgin media superhub 2, which has 5ghz wifi. My wifi card supports 5ghz, and appears to connect at a higher speed when I choose 5ghz.

My question is are 2.4Ghz wifi antennas going to work well at 5ghz? I can see a few antennas sold as 5ghz but they dont look any different to normal ones.

In reply to a post by Livebox:

My question is are 2.4Ghz wifi antennas going to work well at 5ghz?

Extremely unlikely.