Getting Latest Posts from different blogs on 1 page

hi,
its my first post here,hope i will get the solution. i have 3 wordpress blogs using one database named “operating_systems” with 3 different prefixes e.g

for “Windows Blog” prefix is win_

for “Linux Blog” prefix is lin_

for “Macintosh Blog” prefix is mac_

now i want to list recent posts from all blogs in my home page e.g

In the home page under Heading “Latest from Windows” all latest posts from windows blog will apper
and heading “Latest from Linux” will contain all latest posts from linux blog and so on…
the problem is that i did’nt know how to creat custom mysql query and than show the result through posts query.
if any body have any idea please share here,
i’m waiting for ur kind replies
thanks