One of my hens was looking thin and then I saw a roundworm in droppings this week-ugh! /img/smilies/sickbyc.gif Based on various posts on this site, I decided to worm my hens with Valbazen (albendazole).  Afterwards, I had some serious second thoughts, which led me to do some additional investigation, which ultimately calmed my nerves.  The recommendation to use Valbazen was a good one!  Thanks to BYC! /img/smilies/love.gif
The article that calmed my nerves describes research done on broilers using 3 dose levels of albendazole (5 mg, 10 mg and 20 mg/kg body weight) and then measuring the effectiveness by doing necropsy analysis 7 days after treatment.  Here is the link to the journal article: 
http://japr.fass.org/cgi/content/full/16/3/392#T1
Summary of study findings and how Ill manage my flock:
1.  There was a high incidence of worms in this 1 year old flock, maintained on litter.  Incidence:
o  Ascaridia galli (roundworms)73% adults; 80% larvae,
o  Heterakis gallinarum (cecal worms)100% adults; 73% larvae
o  Capillaria obsignata. (capillary or thread worms)100% adults; 100% larvae
o  Raillietina cesticillus (tapeworms)53%
2.  There were no adverse effects of albendazole treatments on bird appearance, behavior, apparent appetite, and weight gain.
3.  Good control was seen at 10 mg/kg for all worms except tapeworms, which required 20 mg/kg for control.
4.  Through other medical websites, I found that albendazole is used to treat humans with worm infections.
5.  Conclusions:
o  Since there is a very high incidence of worms in chickens raised on litter, I plan to worm my chickens 2 times per year, or more frequently if I observe worms or weight loss.
o  I will use 10-20 mg albendazole/kg body weight, which translates to:
-  2 pound chicken ~0.1 ml Valbazen
-  4 pound chicken ~0.25 ml Valbazen
-  7 pound chicken ~0.5 ml Valbazen
o  Ill not eat the eggs for 2 weeks, although since albendazole is used in humans, this is probably not essential.
I hope others find this useful.