[iTunes] Manually Manage Music and Videos feature

[Michael Prete]

I have an iPhone 4 with iOS 4.1 and iTunes 10.0.1. When I connect my  
phone to iTunes on my iMac and select by phone in the left hand column  
under "Devices", it seems that the "Sync Music" check box under the  
"Music" tab becomes unchecked. If I check the "Sync Music" check box  
there and return to the "Summary" tab, I find that the check box for  
"Manually Manage Music & Video" has become unchecked. This seems  
highly counter-intuitive to me. I want to select certain albums,  
playlists, etc to be synced to my phone since I don't have enough  
storage to sync all my music, and to me that indicates "Manually  
Managing..." my music.

What the heck is going on? It seems that if I want to continue to  
select only certain specific parts of my music library, I must give up  
checking the "Manually Manage Music" checkbox. Any insights into how  
to properly use these features or why I can't have both boxes checked?

Michael Prete
2.0 GHz G5 iMac, 17"
1.5 GB RAM, OS 10.5.8
iPhone 4, iOS 4.1
500 GB Time Capsule