IP Networking

Hi

I have a question related to load balancing.I have two separate internet connections with 2Mbps speed and i would like to aggregate this two connections intro one connection with 4Mbps.Is it possible to do that, to put a Linux or Unix machine as a gateway?I read some stuff to split the traffic on one side ftp,smtp.... and on the other side http,telnet... but i don't want something like this and if it is necessary to buy a special router i think it should be possible to use a simulator to do that like for Cisco "Dynagen Dynamip" or JunOS on a virtula machine.
I searched the whole internet and i didn't found any solution , but it must be possible to do that or not ?????

Thanks in advance

You can make your box into a router or a NAT even if you want.
zebra is one example of software that does what you want:
GNU Zebra -- routing software

Here is an overview of how to do it with zebra:
Build a network router on Linux

Thanks for your replay i checked the how to but i think this will work only as a fail over (if one link is down the other one will take the traffic) i want to use both links to speed up the internet connection.
Any ideas?

Sun had a product called "sun trunking". I have never used it but try googling. If I am not mistaken, it lets you aggregate multiple network connections as one.