I am using Dual Boot Vista and Osx without any problems.
Try reading this guide. It has tons of info and I personlly feel the best guide out there
http://www.insanelymac.com/forum/ind...howtopic=39253

Since you have already installed both, only focus on the section explaining boot loader

Setting up with BCDedit is the easy. I havent figured out the graphical way of doing it(ie. easybcd)

You might need to copy chain0 from OSx to your Vista root. and rest is explained in the guide wonderfully.

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Ideneb 1.4..Voodoo kernel with 10.5.5 seabelt fix.
AMD 64 Athlon 3000+ 3.5GB RAM
Seagate 500GB SATA...Seagate 160GB SATA.....Seagate 40 GB non SATA....320GB IO-DATA USB external...Logitec 80GB External USB
XFX nvidia 8600 GT 512MB..QE/CI enabled with 9f23
ADI AD1986A(Modified version of 1986 AppleHDA) all jack working, but without any volume controls
Nvidia Ethernet ..nforceLAN kext
Everything else works!!