Interoffice memo software needed

[sakumar79]

Hi,
I work in an office with about 20-25 staff and a corresponding number of computers. Currently we are passing memos using paper, but there are problems such as misplaced memos, memos discarded before completion, etc. I am looking for a memo software with specific features such as:

1. Must work in LAN, each staff will log in to the software when they sit at the computer
2. Must have facility to have admin account(s) that have rights to add/delete staff
3. Must have setting to allow only admin account to post memos.
4. Must have setting to allow memos for specific staff instead of everyone.
5. Must have setting to specify priority as Urgent or Normal
6. Once staff marks the memo as "Done", it must inform the admin who should be able to reverse the same if he/she feels it is not yet completed.
7. When user logs in, they will be presented with memo list on screen - they can minimize or close or mark as read as required

If anyone knows any such software, please let me know... While I prefer freeware, I am willing to pay for it if it is having all above functionality at decent price...

Thanks in advance
Arun