Hello,
You can download the software here:
http://www.keil.com/demo/download.aspIt seems you're using 8-bit AVRs. If thats the case, then I wouldn't recommened Keil C. I use Keil C mostly for working with 8051/8052 in conjuction with the Ultra-High Speed DS89C420. This is particulary my favorite microcontroller, offering a whoppin' 33MHz (33MIPS!) with a clock doubling feature, comes in 16/32/64kb flash memory, 8-bit ease and still comes in a DIP package.