Netbooks are ultra-portable at the expense of a DVD drive (and a lot of scrolling), but they do have USB ports. And with Windows 7, Microsoft has made available a nifty tool:
Windows 7 USB/DVD Download Tool
But if you don't have 7 (because people think XP is that great light-weight operating system of all time and Vista was a mistake, which it wasn't):
Format your USB Memory Stick as FAT (not FAT32 or exFAT) and then if you have a Vista DVD, you can run "d:\boot\bootsect /nt60 e:", where "d" is your CD/DVD drive letter, and "e" is your USB drive letter. If you are going for XP, download bootsect (or really, never trust anyone, and just copy that file from someone who does have one of those disks) to your desktop, and then run "c:\docume~1\username\desktop\bootsect /nt52 f:", where "username" is your username.
Then copy the contents of your CD or DVD to the USB and then attach it to your netbook and reboot. If your netbook doesn't automatically boot to the USB stick, then the boot order isn't setup correctly; either boot into the setup (F1 or F2 or something like that when you first boot up) or it would be easier to use the one time boot menu (F9 or F12 or something like that) and then pick the USB flash drive.