Thanks for spotting that installer issue. Should be fixed now.
I am tempted to start using DirectX 9 in all my games but I'm still worried that there are a fair few computers that don't have it installed (my father-in-law's Windows XP machine didn't for example). I have to weigh up how much better one of my games would be with DirectX and how many people would be put off playing if they were asked to install something before even being able to play.
I think Vista and Windows 7 always come with DirectX 10 and 11 installed and they both can run DirectX 9 apps so the problem may lessen over time.
I'm also worried that MS may change things in the future (maybe drop support for DX9!) and my games will all need a re-write! If I stick with simple GDI then the games will be slower and jerkier but at least they should always work.
My DirectX code does detect if you don't have DirectX installed and use GDI+ instead (see
http://www.windowsgames.co.uk/blitz2D.html) so it should look the same but run more jerkily.
I've uploaded the new DirectX version of Football-o-saurus which I've been holding off for a while because of my concerns. I'll see what feedback I get and maybe gradually update the other games.