In the manga, Dragon Slave is written do-ra-gu su-re-i-bu in

katakana.

How the kanji form could be romanjised, I have no clue. 

However, doragu sureibu would suggest that the transliterated form

is

dragu slave or dragu slebu (which makes absolutely no sense.. ^_^)
so, according to the manga, the name of the spell is Dragu Slave.
This is also quite close to how it's pronounced in the anime.
The first word is either 'dragu' or 'dragon' or something in

between,

and the second is without a doubt 'slave'.

In my opinion, the right way to write it is 'Dragon Slave', since

that

'dragu' would be, IMHO just, the Japanese way of saying 'dragon' in

English.

Hmmm...well, if the spell is given as "do-ra-gu-su-re-i-bu", then
it's either Dragu Slave, or Drag Slave. 

The Japanese way of saying "dragon" in English, as most Dragonball
fans (that is, people who have copies of the original episodes/manga)
can tell you, is "do-ra-go-n".  

Then again...there are often multiple ways to translate an English or
other language word into katakana, so...<shrug>

--------------------------------------------------------------------
[This space for rent. E-mail:
they-killed-kenny@you.bastards.com]
---
The Eternal Lost Lurker
My hair is purple. I wear mirror shades.
Am I cool or what?
EternalLostLurker@worldnet.att.net
http://www.geocities.com/Tokyo/Garden/9502

I have your insect collection. Cough up $10 grand,
or the dung beetle gets it.
-------------------------------------------------------------------