DirectX Update Problem

[reddragon105]

Not sure if this is the right place for this question, but here goes:

I currently have DirectX 9.0b. when 9.0c came out i downloaded it and tried to install it. it said 'To start installation, click next', so i clicked next, and it instantly told me 'Installation complete'.
it did not look like it had done anything, and when i checked dxdiag, sure enough, i still have 9.0b

this hasnt been a problem until now, where i have some more recent games that come with 9.0c. they are checking my DX version and refusing to play until i update it. of course, i can not update it as this happens every time.

so im thinking there must be a way i can uninstall and reinstall DirectX, or a registry entry i can change someplace. any help on this?