Open Suse, slackware and Windows Vista triple booting

I want to install Slackware, OpenSuse and windows Vista and make my system a triple booting system. Which is the right order to do it.
Intel Pentium 4, 2.66GHz
1Gb RAM, 80gb and 120gb HDDs

Further, When I installed Vista and slackwar first and then tried Open-suse it did not recognised Slackware, but recognisede Vista.

You should add slackware root partition in Grub