Update - I installed windows 7 over my vista os with the same driver and on my first restart, it happened again.
Being a fresh install and not having all the drivers for things like usb, gpu and monitors, and not remembering where these drivers were located in the pc, I allowed the device manager to search online. I also did the same for the router and it downloaded one I had not previously found online or through the manufacturer website for the product. The driver seems to have fixed the problem because I have had no problems with startup since then.
I guess it was the driver then. I don't know what could have caused the old driver I was using, which according to the linksys website was the latest and specific to the routers hardware version, to cause problems all of a sudden after years of usage. I don't think it was a Vista specific problem since I got the same startup loop after installing Windows 7. For now I'm just glad my pc seems to be working fine again and I was able to sort it out and save a few dollars