Is it true that any external hard drive made for the PC, can be used by a Mac running Lion?
2 things:

1) They are not "made for" PCs, they may simply come pre-formatted.  If they are USB, they will almost certainly work with any OS known to man that supports USB

2) NTFS support is read only, you cannot write (without 3rd party software) but you can format as Fat 32 or EXFAT etc and have the drive be read/write by almost any OS including Windows/Mac/Linux etc/