Sorry Celtic, didnt answer you question.
If the loom connection is the same, then in theory yes, the hallogen headlight clusters should swap straight in.
However, whether this will throw up any
warnings because the power drain is is differnet to what it expects, I am not sure. (xenon power drain is about half of the drain of halogens, but I may stand corrected on the exact amount).
I have to admit, though, if my ballast swap isn't succesful, I would seriously
look at retrofitting hallogens. Quality of light asside, the vulnerablility of the Lag design xenon system, and the time/cost to repair it when it does fail is a strong argument to ditch it.
The price of a couple halogen headlights from the breakers yard is probably less than replacing the ballasts with Valeo ones. Then there is the price of the xenon bulbs. (yes, I know they are in theory expected to last a long time, if not the life of the car... but hey... its a renault!)