is it possible to install macosx on an insprion 1520 that already has linux and windows xp installed on it? maybe install macosx on top of this to create a triple boot? i don't want to install macosx on an external hard drive but on the same internal drive that store linux and windows xp. i am using grub 2 currently. is this possible? please help a noob out!

i've searched and asked on insanely mac but they've been of no help. they say to do a fresh install but how do i do this without having to do a fresh install?

Well it depends if you have any free partition to put macosx on. If xp partition is the last partition, you can shrink NTFS and free up space.

If you have only two or three partitions (i suppose you have an MBR partition scheme), you can make a third/forth primary partition which you dedicate to OSX.
Use a tool like GPartEd (comes on most linux live cd's) or for example Easeus' partition manager for windows (google it, it's free) to shrink one or more of your current partitions to free up space (at least 10 GB). Then, you create a new partition within that new space, and you install OSX on that one.
Chameleon bootloaders work fine on multiboot systems, as long as you are only using primary partitions (not extended + logical ones!) or if you use the GPT partition scheme.