I had to buy a new hard drive for my laptop. I don't have the restore disk for the OS, now what do I do?

I replaced my hard drive on my Gateway laptop. The new hard drive of course comes blank. I don't have my restore disk anymore, so I used my restore disk from work that is for an Emachines computer. Needless to say, the vast majority of the programs are non existant. How do I get my laptop up and running like normal from this point. I talked to Gateway and the restore disk is no longer available to order. Do I need to purchase a whole new operating system, or is there an easier avenue. And lastly, I have a cable modem, with a wireless access point (for my Wii and Tivo), will this suffice to be able to get a wireless signal to my laptop as well? Thanks for any assistance anyone can give me.