Play around with the showwindow, desktop, and autocenter properties of the child form. I've never tried it but if you can't get that to work, you can always take the position of the top level form using sysmetric() and the size of the top level form using height and width, then using the height and width of the child form and a little creative math you can center the child form by setting top and left.
HTH
Eric Kleeman - EDS Consulting Services
MCP Visual FoxPro
MCSD C#.NET
Hua Hin Thailand
Los Angeles California