I want to install linux on a dual boot (with winXP) in the absolute safest way (I also want excess resources for both partitions). Therefore, I am wondering if I buy an external HD for my laptop and made it dedicated to linux, would this be 100% fail-safe in terms of not messing with my other HD with XP at all? (last time I did partitioning I used partition magic and installed linux fine, but then windows wouldn't load anymore, and I also wasn't a fan of having to split up my already scarce memory). Thoughts/suggestions?

Nothing with computers is "100% fail-safe". Be sure to have all important files backed up before making ANY changes.

How scarce is your "memory" (by which I assume you mean HD space)? You could simply install a larger internal drive.

I have 2 hard disks in my box. there are about 5 Linux distros on the second HDD which has 5 seperate partitions (40Gig). the first Hdd is partitioned into 5 also but it's 250gb and my ubuntu had a great deal of trouble trying to configure it. that's why is switched my open source OS's to the second HDD. To access it i use the system bios to choose which HDD i want to boot from first and grub handles them perfectly. i'm still thinking of putting a linux OS on the last partition of the 250gb. i use an AMD 64 athlon. hope this helps. chow