Seems like grub did not install into the MBR, for whatever reason. I'd recommend just using the Windows bootloader to load Linux. There's plenty of tutorials out there, the gist of it is - boot into Linux using a bootdisk, or use your install cd to access Linux rescue mode. Copy your linux boot sector, "dd if=/dev/hda2 of=/linux.bin bs=512 count=1". hda2 should be your boot partition, change it if necessary. Move linux.bin to your C: directory via a shared FAT partition, a floppy disk, or any other way. You'll need to reboot into Windows to finish the operation. In Windows, edit your C:\boot.ini file. Add the string
on a new line. You will need to change your settings to view hidden files and system-protected operating files to edit it. Once it's done, save, reboot and see if it works.