to Bob-H:
I would suggest getting an 8Gb or larger USB flash drive, creating an .dmg file of the DVD (assume it's a dual layer), mounting the .dmg file & copying the mounted "disk" onto the flash drive. Since most modern macs will boot from USB (if you hold down the option key while you boot - then choose the appropriate boot volume), this will let you recover from a USB drive. Then, you won't be locked in to the DVD drive process.
When Lion comes out, do the same "install to USB" procedure with the downloaded image file.
~mrZ
miniCAD/VectorWorks user since miniCAD 0.9
VectorWorks/RenderWorks Designer 2011 SP3
SL 10.6.7 macPro 3.33GHz 6-core Xeon, 16GB/1TB, Radeon HD 5870