I back up my Windows PC's in two ways:

1. I have a set of external USB2 80G harddrives that I rotate between my home/studio and offsite onto which I do regular backups. Because the USB2 connection is faster than my wireless network, I sneakernet the drive to each PC and run its backup script.

2. I have a USB2 Memorex True8X DVD writer that I also use to write backup DVD's, mostly of image data from my studio PC (I'm a photographer) , but I also pass it around to the other PC's sometimes.

What are my options with Linux? My external HD's are formatted with NTFS - can they be mounted on my Linux system?

Are there appropriate drivers for my Memorex DVD writer?

No, linux cannot write to NTFS disks. It can read from them but it is not enough for you I guess.
Consider reformating to FAT32, it is ok with both linux and windows.

No, the backup utilities I use create really big files (they basically take the whole backup set and create one huge, compressed, encrypted file). Bigger than 4gig, which is the Fat32 limit.

I suppose I could create 2 partitions on my external HD - one NTFS and one FAT32.