I have recently created a dual boot system (Win XP Pro / Fedora C1) from my previously Win XP Pro only system . I have 2 SATA 120GB HDD's one for each OS. Is there a way to use a windows emulator (free or $) to run the XP already on the C drive (sda) from inside the Linux OS on the D drive (sdb).

I know that emulators exist to run windows programs in Linux, but I specifically want to access the OS that already exists (and all the programs and data therein). I went dual boot (rather than complete Linux) precisely to avoid having to reinstall all of the things that I still need in Windows (atleast temporarily until I find suitable replacements). If an emulator requires reinstallation of these programs then it doesn't do me much good.

Wine won't do that. In fact, Wine Is Not an Emulator (aka, the name WINE). Wine is a implementation of the windows libraries.

VMWare will let you try to do this, but I don't recommend it. The reason is VMWare emulates computer hardware. Not your specific computer hardware, just some generic x86 computer hardware. If you try and boot your existing windows install using VMWares emulated hardware it'll either a) not boot at all, or b) screw up all your drivers so when you boot back into it regularly things will be all messed up.

And just so you know, VMWare doesn't let you run Direct3D stuff...

I wanted to try this first , but it isn't recommend , i had a look in the pdf manual of workstation (3) and there it was said that it isnt a good idea to try and run an existing win XP in VMware , read the manual of your vmware version , perhaps the newer versions do support it , and when it is possible (if its possible) the manual will tell you how ..