Help with Internet Configuration

I had posted under Hardware, but I think it should of been here:
Starting new biz that requires my current PC to be hard wired directly to the internet. This PC currently provides wireless access to a laptop and addt'l pc. If I work for this co. I can no longer provide wireless access to the other PC's due to security isssues. I currently use a Vonage Motorola router VT2542 that provides VOIP and Wireless in one router. I will have to remove VOIP and have an analog phone line attached to the computer.

I was told by the company I will be working for, that I can share the internet line as long as the computer I am using for them is hard wired to the internet. What I failed to tell them, is that the laptop is used for a different business and it relies on my PC for wireless internet access. Is it possible to share an internet line without it being a wireless connection? I have the capability to go back to wired if need be, but not sure if there is hardware out there that will allow me to do this? My cable co. mentioned a switch box? But said only one PC could use the internet at one time? Is this true? The only other alternative would be to purchase an additional internet line at $35.00/mo.

If I can share the line, I was going to make my other desktop the provider of a wireless network to the laptop and it would be the provider of my Vonage phone lines.

Another thought, instead of an addt'l internet line, buy a wireless data plan for laptop and have desktop share wireless connection with laptop? But, I don't think my vonage lines would work properly that way?

Sorry, don't mean to be so long winded. I am very confused and I need to get the best setup at of course, minimal costs but also one that makes the most sense.

Thank you to anyone can help.