If by that you mean an optical drive, yes you can but you would have to install the OS using something else other than the disc.

Well, it's not strictly needed anymore, you could have the installation files on a USB drive for example.
But I'd say get an optical drive anyway, they are so ridiculously cheap nowadays that you wouldn't save much.

If you're in Canada go to www.pricecanada.com and do a search on liteon ihas124 it's a 17$ dvd-burner and works well. Otherwise, go here:

http://www.google.ca/search?hl=en&safe=off&q=install+windows+7+from+usb&aq=f&aqi=g10&aql=&oq=&gs_rfai=

You'll find many resources to install Windows 7 or Xp on a computer without a cd/dvd drive (such as netbooks).

You can also use other programs to install an OS through your network but that's more complicated.

Good Luck!