ciao, scusa per il ritardo... il menu a tendina l'ho creato con un elenco :

<ul class="menu" id="menu">
[*]Home

[*]
Soluzioni
<ul style="left:11px;">
[*]Prova1
[*]Prova2
[/list]

[*]
[*]Area Clienti
[*]
[*]
Contatti
<ul style="left:17px;">
[*]Contatti
[*]Lavora con noi
[/list]

[*]
[*]Referenze
[*]
Azienda
<ul>
[*]Missione
[*]Soluzione Tecnologica
[*]Storia
[/list]
[/list]

E il foglio di stile è così composto:

ul.menu {

background: transparent url(img/menu.jpg) no-repeat scroll 0 0;
float: left;
height: auto !important;
list-style:none;
margin:0;
padding:0;
min-height: 67px;
height: 300px;
width: 930px;
}

ul.menu * {margin:0; padding:0;}
ul.menu a {
display:block;
color:#555555;
text-decoration:none}
ul.menu li
{position:relative;
float:left;
margin-right:0px;}
ul.menu ul {

position:absolute;
top:67px;
left:23px;
background:#D1D1D1 none repeat scroll 0 0;
display:none;
opacity:0;
list-style:none;}
ul.menu ul li {
border-color:-moz-use-text-color #AAAAAA #AAAAAA;
border-style:none solid solid;
border-width:medium 1px 1px;
position:relative;

border-top:none;
width:148px;
margin:0; }
ul.menu ul li a {
display:block;
padding:3px 7px 5px;
background-color:#FFFFFF;
font-weight:bold;
text-align: left;}

ul.menu ul li a:hover {
background-color:#FFFFFF;
COLOR: #0096D2;
font-weight:bold;}
ul.menu li a:hover {COLOR: #0096D2;}

ul.menu ul ul {
left:148px; top:-1px}

ul.menu .menulink {
padding:0px 1px 25px; /*0 1 25*/
font-weight:bold;
width:80px; /*Impostata da PINI era 105, impostata 80*/
font-size: 9pt;
margin-top:26px;
onFocus: this.blur();}

ul.menu.menulink a:active{background: #fcf; COLOR: #0096D2; text-decoration: none;}

Infine lo script:

var menu=function(){
var t=15,z=50,s=6,a;
function dd(n){this.n=n; this.h=[]; this.c=[]}
dd.prototype.init=function(p,c){
a=c; var w=document.getElementById(p), s=w.getElementsByTagName('ul'), l=s.length, i=0;
for(i;i<l;i++){
var h=s[i].parentNode; this.h[i]=h; this.c[i]=s[i];
h.onmouseover=new Function(this.n+'.st('+i+',true)');
h.onmouseout=new Function(this.n+'.st('+i+')');
}
}
dd.prototype.st=function(x,f){
var c=this.c[x], h=this.h[x], p=h.getElementsByTagName('a')[0];
clearInterval(c.t); c.style.overflow='hidden';
if(f){
p.className+=' '+a;
if(!c.mh){c.style.display='block'; c.style.height=''; c.mh=c.offsetHeight; c.style.height=0}
if(c.mh==c.offsetHeight){c.style.overflow='visible '}
else{c.style.zIndex=z; z++; c.t=setInterval(function(){sl(c,1)},t)}
}else{p.className=p.className.replace(a,''); c.t=setInterval(function(){sl(c,-1)},t)}
}
function sl(c,f){
var h=c.offsetHeight;
if((h<=0&&f!=1)||(h>=c.mh&&f==1)){
if(f==1){c.style.filter=''; c.style.opacity=1; c.style.overflow='visible'}
clearInterval(c.t); return
}
var d=(f==1)?Math.ceil((c.mh-h)/s):Math.ceil(h/s), o=h/c.mh;
c.style.opacity=o; c.style.filter='alpha(opacity='+(o*100)+')';
c.style.height=h+(d*f)+'px'
}
return{dd:dd}
}();

Grazie!