Either of those VGA Boxes look to be fine. BUT, I need to know the model number and such of your monitor, so I can lookup your monitors specs and check if it has support for the required resolutions.
But never the less, I would most recommend CRT based monitors for playing Nintendo Wii games, due to the Native Resolution issue of LCD based displays, which I have mentioned of many times on this forum.
Ohh, and incase you don't already know... you will need the Nintendo Wii Component cables to use these VGA Boxes, which maybe be tricky to get hold of.
BTW, maybe you will find this thread useful.
I almost forgot to mention... if your monitor has Component ports, then you won't even need a VGA Box!