The Dual install depends on the version of windows - XP Pro + Ubuntu 12.04 LTS 32 Bit has worked for the last 3 years without probs - Dual boot using grub (now old fashioned) (And yes it warns you about installing a EXT3 partition).
Ubuntu can also be installed using something call wubi - where the Unix Sys exists as an application in the Windows partition - Its not as resilient to failures as a separate install. - I have no direct experience of using this. Not to be used under Windows 8.
Now for the gutya's I'm not sure about installing a second partition under windows 7 and definitely Windows 8 - Microsoft has introduced a system of protecting the boot system called secure boot that prevents alteration to the boot record.
From Wikipedia
"Windows 8 supports a feature of the
UEFI specification known as "Secure boot", which uses a
public-key infrastructure to verify the integrity of the operating system and prevent unauthorized programs such as
bootkits from infecting the device" - wubi gets around this according to Ubuntu"
Booting Ubuntu (there are other Linux operating systems) from USB seems a good idea.
Edit: *** Warning *** Wubi is not supported after Ubuntu 12.04 - sorry about that.
CAT III