I still use Paint Shop Pro 6.0 every single day. It runs flawlessly in Windows 7 if you set compatability mode on the EXE to "Windows 2000".
Version 6 was the last good version before Corel muddled up the interface and made it bloated. I can still do some things in 2 clicks that my coworker needs 5-15 clicks to get done in Photoshop. It surprises me to know some things are still so "complicated" in photoshop, just by how many clicks/steps are needed. I'm sure PSP 6 is borderline abandonware at this point, released 16 years ago in 2000! I upped the full version here (15mb): http://www.filedropper.com/psp6
Wine! For older programs it works especially well. I've had a legal copy of Photoshop 7.0 for Windows since middle school and I have been running it without any problems since then.
Version 6 was the last good version before Corel muddled up the interface and made it bloated. I can still do some things in 2 clicks that my coworker needs 5-15 clicks to get done in Photoshop. It surprises me to know some things are still so "complicated" in photoshop, just by how many clicks/steps are needed. I'm sure PSP 6 is borderline abandonware at this point, released 16 years ago in 2000! I upped the full version here (15mb): http://www.filedropper.com/psp6