Designing PCR primers

[Taunja Lee Palmer-Stone]

Is there a Mac freeware/shareware programme for designing PCR primers? 
(and if there is where can I find it).  I have two sequences that I would 
like to use as primers in a bacteria which favours G/C in its codon 
usage.  Since I am using two consensus sequences I am somewhat limited in 
my choice of primer sequences.  I know people who have had mixed 
experiences with designing PCR primers.  Some didn't check  
their primers and later couldn't get their PCR to work because the two 
primers didn't anneal at the same temperature.  Others didn't check and 
got good results (different primers of course).  Which scenario is the 
most prevalent?  I would like to check my proposed primers before I get 
them synthesized.  Any PCR gurus out there with advice/comments?  Also, 
are there any pitfalls to using I in PCR primers?

--
Taunja Palmer-Stone
tlpalmer at acs.ucalgary.ca