Click on the arrow besides Welcome domain name \ user name and then click on My Settings
There are following options Account , Name, etc.
Check Name option, if it will show you Domain name \ user name then you has to change the display name in user’s AD attributes because this information is directly fetched from AD via SSP.
After change in Display name in AD attributes recheck user profile properties under SSP user
profiles and properties
Please let me know in case of any queries