Linux and other Unix based OSes are inherintely more secure. The root account is used to install software, and other stuff, but not to check e-mail, where most viruses are transmitted. In Windows, most people use the Admin account to do everyday work. In Linux/Unix-based OSes, most people (excluding Lindows users, BTW, never use Lindows) use a normal user account. Only root has access to the main part of the filesystem, and normal users only can access their home directories, which can easily be wiped clean. And, no, viruses cannot "escape" unless someone stupid changes the owner of the file to someone with power. Also, when a file is transmitted, it is not executable. In Windows, give a file .exe or .scr and it can be executed, but in Unix-based, you must change the file permissions to allow it to be executed in the first place, so nothing is automatically executed. Also, most *nix mail clients don't display HTML mail be default, but they display the code, or cut off most of the formatting, and display plain text, so no images, or applet, or whatever.
The exploit was only used once, to crash a couple machines before it was found and fixed. Most Windows exploits crash many more machines than that, before patched. And in Linux, if something isn't getting patched soon enough for your liking, patch it yourself, and then submit the patch for review, before it will be put into the kernel source tree.
