What type of mobo do you have?
Try this before you reply too. Disable anything you don't need while flashing, on board sound, on board nic, secondary IDE, firewire, and any other expansion card you may no require. Also, you might want to load the fail safe settings of your mobo. Once this is done IRQ 15 should be available, since it is commonly reserved for the secondary ide. Assign IRQ 15 to the pci slot the VIA card is sitting in. When you boot up, shortly after post there is IRQ summary, you should see IRQ 15 assign to a RAID CARD or something of the sort. If so you are in good working order. You should be in windows with the card detected. Check your device manager. Oh I have have also heard that in you turn on enhance ide on the bios it help, try both.
Let me know what happens. By the way you don't necessairly need the card installed in windows, i for one have never installed it, nor have loaded drives. I just make sure port 15 is assign, that it is the irq summary and reboot and flash.