In order to use boot screens from 1.5 on 2.1 ROMs, you need to remove the current bootanimation.zip from the phone.
(On Villain ROMs, it is located in /system/customize/resource/ - others may vary)
Then flash the downloaded file; this puts the folder 'bootscreen' into /system/media/
If you want the original one with the little Android hiding behind 'HERO' download and flash the attachment below this post.
Despite what others say, the old (1.5) format bootscreens do
work in 2.1, however, I'm yet to get the bootsound working.
HTC Incredible S
HTC EVO 3D
HTC One X