I recommend PocketShield
http://pocketshield.netserver01.com/
or s2u2
http://s2u2.ac-s2.com/
s2u2 is very customizable.
What rom or version of widows mobile and sense ui are you using? Cookies home tab mod has three lock screens to choose from and are also very customizable.
http://forum.ppcgeeks.com/showthread.php?t=109863