Okay, so for PWNing the ACT, I recently got a FreeAgent Go (320MB). It is an excellent drive, very small and very surprisingly fast, and it has done everything I wanted it to, and performed very well. I recommend this drive.
However, I do not recommend trying to do what this thread suggests on a MacBook. For the past three days, I've been trying to get this to work to no avail. I tried rEFIt, native tools, everything, I even installed the kernel to the internal harddrive, it doesn't work. (Not Apple's fault, however; they just use a totally different technology [EFI] than PCs, and cannot be expected to emulate perfectly.)
Another thing I learned is that XP is notorious for being unfriendly with external drives. GL to anyone who tries with it.
*here's to Ubuntu trying its hardest to work with EFI*