2009/8/4 Joe Murithi Njeru <joe.njeru@gmail.com>

Hi Odhiambo,

IPS stands for Intrusion Prevention System.

Nice. I thought Investment Promotional Services ;-)
You should have used IDS/IPS since you need to detect/prevent, or?

The dual links provide redundancy should 1 provider be down. Typically
the two links will be:
an ADSL/3G link.
a Fibre/Wireless link.

Content filtering involves blocking facebook, XXX sites plus whatever they require blocked.

A FreeBSD box would easily address your problem, moreso if you can use PF and craft good rules for it to do the load balancing. PFSense would have been handy for this, given the GUI, but I am not sure how easily you'll get to install the other applications required, given that I have never used PFSense beyond running it from the CD.
I have once played with PF and load balancing of two links sometimes back but crashed that disk (it was a SCSI one) and cannot recover it. I have taken some time to try and remember how it went then, even the PF.conf that I believed I shared on the net but cannot locate it using google. The closest I've come to implementing the load balancing portion of this is http://tinyurl.com/mkopb7. Ignore as much as you are willing to and delve down to the PF rules. They should work well with FreeBSD 7.x if that is what you decide to use.
Once you bag that, the rest is damn easy:
For content Filtering - Use transparent proxy with Squid and Dansguardian (squid from ports, Dansguardian by hand!)
For IDS/IPS - Snort+ACID+MySQL (easy to install from the ports)
For VPN - use mpd5 from the ports.