I'd just like to say that playing random notes in a scale may not sound that interesting to a listener. Knowing the scales should help you play those things that come up in your head and a great way to come up with new ideas is actually to copy licks, phrases and whole solos from good improvisers, and try to understand how they think when they improvise. A good way to learn licks is using the Winamp real-time pitch control plug-in and slow down mp3 or wav files to half speed. Much more comfortable than sitting with a CD player and listening to that solo again, again and again...