Mikrotik Routing

Hi all

I have one site with a PPTP server (call it HQ) and 3 client sites that connect to HQ with PPTP clients.
All is working well and can ping from HQ all client site ip subnets and vice versa, meaning from client site I can ping HQ subnet.

HQ and client sites is geographically kilometers apart and all sites have ADSL connections.

My question is : I want to manage HQ and client sites all from my business premises, meaning I want to ping all client and HQ sites from my Mikrotik located at business premises.

All the sites have Mikrotik RB951G routers.

What is the best routing approach so that I can manage from my business all client PC’s at every site, ie MS Remote Desktop or MS Remote Assistance?

I just need some advise to steer me in the correct direction, will read and study all the relevant wiki pages.

Best regards
Marnus