Dragon Knight is a wonderful series. Played them a few times. The PC-Engine versions don't have the pr0n, but they are full remakes of the computer versions. All of the them got a major graphical over haul, CD audio by T's music, full voice overs, and an automap.
Now the PC versions have the boobies, but they are very old PC rpgs. 1 and 2 don't even have floors and ceilings, just walls. Also no automap, the games actually came with grid paper and a pencil board to draw your own.
They are still worth playing, but I would stick to the X68000 (1-4) or FM Towns (3-4) versions. They are all the same games, only really differences are music chip, and amount of floppy disks:
DK1: MSX- 4 disks, X68000- 2 disks
DK2: MSX- 9 disks, X68000- 4 disks
DK3: X68000 - 6 disks, FM-Towns: 1 CD
DK4: X68000 - 13 disks!, FM-Towns 1 CD
X68000 versions of 3 and 4, do have hard drive install options so you don't have to floppy swap. DK2 on MSX is a floppy swap nightmare, trust me, I actually played through 1 and 2 on my real MSX.
Also the X68k has the best FM chip of all the computers, and has the best music. Though the PCE versions have amazing music which is totally different. There are also NEC PC computer versions, but I know little of them, but again should be identical. The X68k is way more powerful then MSX, but the games are graphically identical, only the resolution is higher on X68k...