upgrading MTB and some OT

I'm thinking about upgrading my old MTB. First upgrade wuill be a new
set of V's. I've been looking at Avid SD5 or SD7's. Has anyone go
these, if so what are they like? Some reviews of the SD5's say that
they rust very easily, whilst this isn't a real problem (but why make
MTB kit that rusts?), are the SD7's worth the extra?

Second upgrade may be to convert from 7spd to 8/9spd. Currently the
rear hub is XT. Looking around I seem to have 2 options, build up a
wheel based on a new hub, or get a new 8spd freehub body. The latter
option should take less time and effort, and if I get a hub form ebay
and pinch the freehub body, also cost a lot less. I'm assuming that I
will also need to get a new axle. Anyone know wha the OLN for an 8spd
rear hub is (7spd is 126mm iirc)? Will I need to cold set the frame,
or should I be able to bend it far enough (frame is steel, an Orange
Prestige)?

Now for the OT it I'm going to South Africa for 3 months with work to
Bloemfontein, and goig to take my (hopefully newly upgraded bike)
with me. Has anyone done any cycling in sOuth Africa, what is teh
attitude to cyclists? Also since I have never been ther can anyone
tell me anymore about the place? I particularly need to know how much
the beer is :-). Any help and advie greatly appreciated.

Thanks

Bryan