Homegroup vs Workgroup

Hi, I am a relatively experienced PC user however having moved all my home systems to Win7 (all 64bit), I am still trying to get my head round homegroup vs the good old workgroup that was in XP. All of the systems (a mixture of laptops and PCs hardwired and wireless) are all joined to a homegroup and can all "see" each other but here is where I am having a problem. I wanted to add a folder full of a lot of info I wanted everyone to be able to use) on one of the PCs to the homegroup so I set it up as shared to the homegroup however I cannot get it to appear on any of the other systems - all they display are the standard music, video and pictures libraries ? The only way I can get it to show on another system is by doing the "map network drive" as you would in XP on each of them ? then the contents of the folder can be seen on the other PCs - I would have thought this would have shown under the homegroup in the "my computer" view along with the other libraries. I did make sure I set up the permissions so that everyone could access but still can't get anything other than the standard libraries to show on the other PCs. Maybe i'm not as experienced as I thought I was .....

Any help, as usual, would be very much appreciated.

@Roderunner: It's unnecessary to disable 'require 128 bit encryption' for a mixed Win7 + Vista or XP network. Both XP and Vista support 128bit encryption.