To be honest I've never used packet tracer. I hear it's pretty useless after CCNA level because it's just a simulator, and doesn't use full IOS images, so you can only practice certain features. I started off using physical hardware because it was the only option back in 2001, then dynamips, then GNS3, and now back to physical hardware(rack rentals). By the time I found out about packet tracer, I was way past the CCNA level, so I wouldn't be able to get much use out of it. It does sound kind of cool though. Cisco actually has something called IOU, which allows you to test pretty much anything, but you have to be an engineer employed by Cisco to get your hands on it, so unfortunately I haven't been able to test that either. There are bootleg copies out there, but I'm always nervous about downloading illegal versions of software. You never know if somebody put a trojan or some other bad stuff.