I would do the following,
Start Windows install, do custom disk partitioning. create a main Windows Partition (primary partition, As you say for windows and all programs) of 30Gig, create the data partition(another primary partition of 210 gig) and leave the rest of the disk as unallocated space at this point.
Complete the windows install as normal. Add whatever you so desire to Windows at this point.
If you are a newbie Linux user I would recommend starting with Mandriva Linux (DVD iso here
http://www.mirror.ac.uk/mirror/sunsi...-DVD.i586.iso). When you install this it will ask you if you wish to use unallocated space. You can do this or choose custom partitioning and do it yourself. Linux uses a minimum of 2 partitions, preferably 3 ( / or 'root' a 'swap' partition and a 'home' partition )
Feel free to ask if you want me to pop round to walk you through the first install but to be honest its easier than a windows install, its just that you do all OS, Apps and drivers in one swoop rather than in seperate steps as you do in Windows.(It only takes a single reboot at the end of teh install and its all up and working.)