Zend certified PHP/Magento developer

Can i use two NICs to get double the bandwith to a switch?

I just switched to a 2.5 Gbps down / 1 Gbps up internet connection but my ISP gave me a router with only 1 Gbps ports, I have two network cards on my pc so I was wondering if I could maybe use them both together to use the full download bandwith. I have tried bonding them in the OS (balance-rr on ubuntu) but my speed went down to 100Mbps. Is there a way to do this?