Wndows media player to Apple Itunes

I have ripped quite a few CD's to my external hardrive using WMP11 as my library. They are ripped in Windows Lossless format. I want to purchase a new computer and was thinking of switching to Apple. Would this be an easy transition. Can I hook my external to the Apple and play music off it and use the Itunes setup or would this be to complicated to do. Should I just purchase another Windows PC.
I have a seagate portable hard drive I use for Music storage. The drive was originally used with a Gateway running Windows XP. When I switched to Mac last year I transfered a my files (music, pictures and doc’s) to the seagate. Then I just plugged it into the Mac and transfered the my files. There were no compatibility issues. I have a Power Mac G-5.
Correct me if I'm wrong, I should be able to plug my external into the MAc and have no problems. What did you do to organize your music ? Did I tunes automatically set up a library?
Yes and Yes. My seagate was and still is formated with MSDOS FAT 32 (Windows)and is still connected to my mac and working fine. I used iTunes to import and sort my music. Once on my mac HD I used iTunes to convert 50% from mp3 to apple lossless.
I’m still learning mac and use the following help page: