Assuming you've installed Windows in a dedicated partition, you can image your windows partition to a single DVD. If not - if you're running one large partition for everything - quite a few DVDs will be required to back up everything, which is a total pain in the ass.
Cheapest reliable solution is Terabyte 'Image for DOS', bootable from floppy or CD/DVD, for $18. Byte-for-byte image verification included, and the DVD created is self-bootable.
Better solution is Terabyte 'Image for Windows' + 'Image for DOS' combo for $28. IFW is faster for creating an image, IFD is required to restore a Windows partition.
Speed comparisons for creating + verifying 4GB Windows image to DVD:
- 12 minutes for IFW.
- 18 minutes for IFD.
Hope this helps!