I always get my linux iso from here:
http://www.linuxiso.org/ Before burning the CD, make sure to check the MD5 Checksum.
As for flash animation, Macromedia is working on a linux port to Flash MX. There are 3rd party apps, but they really aren't that good (Alpha Stage stuff). If you already have Flash for windows you can use Wine to run it. I heard it runs fine under emulation. The other option is to use vmware's software to run a virtual machine.