Great choice with the Rallye, though I'm a bit biased
Check out
www.306gti6.com for all the technical stuff, also has a For Sale section which is worth keeping your eye on (though these,as always, are priced at a premium as they're well looked after members cars).
With regards to the 106 GTi/Rallye, they are very quick and nippy and tons of fun. I was going to get one myself but prefered the room of the 306. Upto 60mph they're pretty even but passed that they're quicker thanks to the glorious 3rd gear on the GTi6
P.S - Personally I don't see any reason to get a Rallye over a GTi6 unless you REALLY want one. They're a lot rarer so it's harder to find a good one. They don't offer that much more in terms of performance bar a slight weight advantage. And they have windy windows!?
EDIT - Like
this one. Although as mentioned if there's no record of the cambelt/tensioners/waterpump being changed in the last 35,000miles then IT NEEDS DOING YESTERDAY! Otherwise it's bye-bye engine and a nice £1200 bill