just add stronger welds to the little brackets you have there. if there is too much weight applied to the front, you may have issues, just strengthen it a bit more, other than that it looks solid.
also do you have bearings at the turning points?
here is where you would put the bearings (red)
http://s742.photobucket.com/albums/xx61/kieranm09/?action=view¤t=kev.jpg
for a move reliable steering setup i would use two at each point, as in pic, but you would be ok with one at each point.
What is the diameter of the bar (yellow)
heres what in found on a quick search, but you may find a better offer.
http://cgi.ebay.com/1-2-1-3-8-BALL-BEARING-SET-OF-10_W0QQitemZ370365327867QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item563b7e69fb
what type of wheel are you using?
if its off a dirt bike those already have bearings in them, but if not bearings on the wheels are a must. just measure the axle size and slot in a few of that size bore bearings.