Re: "disk Boot Failure, Insert System Disk..."
Dual boot's are never fun. Always susceptible to problems. I had this issue with a users PC at my job just the other day. We narrowed it down to either his system board having a problem, or the PSU not drawing enough power upon startup to boot properly.
In the end, the boot device priority was missing the HDD slot somehow to boot to. Make sure the HD is set in the boot menu. I'm sure it is, but just double-check, you never know lol.
Other than that, I'd say to be easy on yourself, get a 2nd HD if you want a dual boot so each keeps their files to themselves and doesn't leave too much room for errors. I ran Ubuntu and XP Pro once dual-booting and had a **** of a time fixing them when they eventually came to a headbutt session.
AMD 3400+ 2.4GHz
1GB DDR Crucial RAM