var hImOver = new Array();
 var hImOut = new Array();

 hImOver[0] = new Image(); hImOver[0].src = 'img/btn-register-a.gif';
 hImOut[0] = new Image(); hImOut[0].src = 'img/btn-register.gif';
 hImOver[1] = new Image(); hImOver[1].src = 'img/btn-login-a.gif';
 hImOut[1] = new Image(); hImOut[1].src = 'img/btn-login.gif';

 function hOver(i) {
   eval("document.him" + i + ".src = hImOver[" + i + "].src");
 }

 function hOut(i) {
   eval("document.him" + i + ".src = hImOut[" + i + "].src");
 }