you know what, try 'Dynamic-Photo HDR' its a software that you can download from the internet (its for free) and if you like it you can buy the license (which will basicly remove the watermark from your pictures). This program is much easier than Photomatix and you got different way of tone mapping. Try it maybe you gonna like it!
Cheers I'll give it a go. Been playing with Qtpfsgui this evening which is apparently a powerful freeware. So far it seems better than Photomatix but my images always seem to come out kinda hazy Did you use just the one source image for this or several exposures?
Great use of B&W here! Love the sky and detail . Might just be me, but is Big Ben slightly leaning a degree or so to the left? Anyway great "random" shot - I love it when things turn out better than realised at the time of shooting