Hi, In the very first posts of this blog I linked to a page for converting miladi and hijri shamsi dates to each other. but it seems many of you guys are looking for a program or source code for this. so here are some links for it:
http://www.codeproject.com/KB/vb/Hijri_Shamsi_Date.aspx
http://www.vojoudi.com/vb/vb_date.htm
and here is a Persian Vista sidebar calendar!
click here for general information about hijri shamsi calendar.
I hope this will help ;)
