Don't think anybody does dismounted curassiers for WSS or SYW, as most of the figures for these periods are for massed battle, and there was no battlefield role for dismounted curassiers.
Don't know about SYW dismounted dragoons, but Front Rank most definately does have dismounted dragoons for WSS. The Front Rank French dragoons are particularly good looking, but the British ones are great also. The Front Rank figures are very bulky, so you have to consider if that style is what you want.
There are other makers of dismounted dragoons for WSS and SYW. Imperialist Enterprises has some, but you won't find that company on the web. Dixon is a source you can get to on the web, though photos are not available for most figures. Dixon's War of the League of Augsberg line has dismounted dragoons that are useable in the WSS. I would suggest looking through what Old Glory has to offer. I've got a few of the Foundry WSS dismounted dragoons, which are shorter than the Front Rank ones and don't have the varied poses.
What do you want to use these dismounted dragoons for?
Warren