Log Management Solution

Hi Gurus,
Would need some advice for a Log Management solution for my company.
Our env consists of mainly Windows 2003 and 2008 servers. We often encounter issues pertaining to disk space issues on our servers due to Logs.
This pertain to Windows Event Logs, IIS Logs, DB Logs (Housekeeping is also done),Sharepoint Logs and several application related logs and much more.
We have approximately 70 different OOTB and customized applications in our environment.
We have approx 300 servers in the environment as well.

As such, we need a solution to be able to ;
1) Be able to extract the Logs from Windows (App & Sys), IIS, Individual App Logs ( Ex Sharepoint Logs, AD Logs, biztalk logs) etc into a Central Logging Server repository

2) This central repository could have a drive connected to a SAN with the required space. Ex (10TB)

3) A friendly GUI to check the status of the transfer etc.
Simple email alerting of the transfer would be good.

4) Be able to specify a archival & retention period for the logs before transferring to a NAS or Tape Library etc. The files can be compressed upon transfer to save space.

5) Be able to generate simple reports and extract the required logs for analysis via GUI as and when required etc

6) Not too sure if it can be achieved without installing the agents on the servers.

Need recommendations for any open source programs that can do this or if we need to purchase software solutions to achieve this. Sadly, we dont have a high budget for this project. Any recommendations or advice would be appreciated !

Thanks