Best app to read/write on NTFS drives

I have several PCs that runs on both Windows XP SP2 and Vista. I also have several external drives formatted in NTFS and a USB thumbdrive that is formatted in FAT32.

I plan on getting the new MBP13". What program should i install in MAC to be able to read and write on my external drives / thumbdrive. I don't want to change the external drive's format from NTFS because we still use it for the other PC computers.

Free or paid programs are welcome. I just need the best and most reliable. I don't want a freeware but unreliable software. It's ok to pay as long as it is reliable. The more stable, the better.

Thanks