Again..No.
Even if it were possible to trunk your ethernet cards, the most you would get is redundancy. If the switch, or hub you use is 10/100 then really the fastest line speed transfer rate you would get would be 100mbps.
Even if you could trunk your ethernet ports to increase your bandwidth the max you could get, again theoretically, would be 200mbps. Again if your switch/hub is 100mbps max this is the MAXIMUM speed you can transfer at.
The only exception is if you use a layer 3 managed switch and trunk vlan ports. Then you would have to have a NIC that was at least 1000mbps to get anything over 100mbps.
This is all lan traffic. If you want to increase the speed if your internet connection this is totally irrelevant.
First there is no residential internet connectivity that exceeds 100mbps. In fact there isn't one that exceeds 10mbps. The fastest commercially available internet connection is OC-255 at 13.21Gbps. Again, COMMERCIALLY available. I don't think LECs drop, with the exception of fios(30mbps), fiber to houses.
If your connection speed on your DSL is 768Kbps then that is the maximum speed that you can connect....although i've yet to see one that actually peaked that that speed..:\
The only way to increase your internet speed is to shell out the money to get the next plan up. DSL at it's highest speed will still fall FAR below your lan speed.
Please feel free to ask if you want a more in-depth explanation of LAN and WAN technologies and principles. I think i've been to wordy already. I'm sorry if I sound condescending here, but I don't want you to waste your time and money. I'm by no means trying to ridicule you. I think we all welcome all questions here at techspot.
Hope this helps.