It's depends bro
I overclocked mine to be an X1900 Xt but... you need the proper Cooling solution and the proper psu if you dont want crap your videocard

And you dont need an bios change because if you use ati tool or ati tray tools you had one option to overclock it ! ...
But remember you can overclock to be like it's but you had never the same performance than the real
So it's depends of the price ... if you have an small budget buy the pro
If you have an litlle more budget buy the Xt
But what you do with this videocard?
Dyou had it now
If is for the gaming i recommand you an X1900 gt or X1950 pro .... highly overclockable!... mine yes it's depends of the rev of the card
Well say about what you want to do with your videocard and will choose the proper videocard
Or you want to buy it?