[GRASSLIST:8358] changing projection

[s99171059 at tuks.co.za]

Hi there,

I am really struggling to convert my UTM raster into a readible and viewable
Gauss conform (AKA Transverse mercator, south oriented),clarke 1880 (Grass
6.0.0).  Can someone pleas e give me all the steps, from start to end, on how to
do this?  I don't have much GIS experience.

What I have:
A UTM raster (ERDAS .img format), with approximate boundaries.

What I don't have:
resolution of the UTM raster and the ellipsoid form

I need to convert it to a Gauss conform, clarke 1880 map with the same boundaries 

Thanks for your time,
Kobus