Laptop as a Router????

I currently have my internet through a dsl company called dslextreme. They sent me a modem that takes a standard phone line in and then puts an ethernet cable out. I took that ethernet cable and put it to an Linksys router from which I run two ethernet cables out - one to my laptop, the other to a piece of hardware profivided by Vonage, a voip provider. The vonage device then plugs into a standard telephone providing me with my telephone service. The service and set up has been fantastic.

Here is where I need help. I just bought an Sprint Broadband Mobile card which gives me unlimited data at an affordable monthly rate. This will give me Internet where ever I travel and they have coverage. So if I cancel my dslextreme account I will not have my same configuration. The Sprint device plugs into a usb port.

Woudl it be hard (and feasible) to then run an ethernet cable to that same router and essentially use that router as I am doing now but using the Sprint Mobile card as the source of my Internet? Thanks.

If you have a version of windows that supoorts it, you can use windows ICS (internet connection sharing). And there are other 'aftermarket' software proxy/router programs you could use.