First off, you're doing an MBR setup. Never a good idea. If I'm not mistaken, Vista supports GPT but uses MBR by default.

Second, your OSes are out of order. Leopard/Snow Leopard is picky and wants to be the first OS on a multi-partition hard drive. Since you're on MBR, you're unable to move or resize partitions, you in order to boot OS X you will need to wipe your hard drive clean, boot from iPC or iAtkos, setup the HDD as GUID and make the partitions you need. Make sure you install OS X on the first partition.

I'm not going to walk you through it, there are guides all over the internet for that. Good luck.

---

Mac OS X Leopard 10.5.8 (9L30) | Chameleon 2.0 RC3 | Intel Pentium 4 3Ghz 800Mhz FSB HyperThread 1MB L2 cache SSE3 1MB L2 cache works, cosmetic display of 512KB L2 cache | Asus P4V8X-MX VIA Chipset, VIA-VT8237 Southbridge | AC97 VIA8237 | Dual 1GB 333Mhz DDR SDRAM | nVidia PNY GeForce 7600GS 512MB 8x AGP DVI/TV-Out/VGA [NVinject 0.2.1; QE/CI/QuartzGL/Rotation] | Darwin Kernel Version 9.7.0: Sun Jun 14 20:48:28 IST 2009; Voodoo 2.0 Intel alpha3 :xnu-1228.12.14/BUILD/obj/RELEASE_I386 i386