The pic while nice def' shows that is sweat pants.

If HR allows you to wear sweatpants then i would go for for it. If not then personally i would not because it only takes one person to notice them and may take it up to HR esp' those that have the mentality of "if that person can wear it then why can't i?".

Maybe look for those denim sweat pants like the link below. While they are sweats they really do look like denim jeans so maybe they will be easier to pull off.
http://www.kingsizedirect.com/large...s&ppos=5&Splt=0
http://www.kingsizedirect.com/large...=1&StyleNo=8290