I'm trying to re-create the "Attach File" page using visualforce, but with big files, it is throwing the following error:

Maximum view state size limit (128K) exceeded. Actual viewstate size for this page was 142.438K

I've already been through the forums and the following post --

http://community.salesforce.com/sforce/board/message?board.id=Visualforce&message.id=10488#M10488

I tried commenting out lines to see if it would help, but the error doesn't go away.

 Here's the code --

public class OpportunityAttachFile {
public Opportunity oppty {get;set;}
public String fileName {get;set;}
public List<String> uploadedList {get;set;}
public Blob fileBody {get;set;}

public OpportunityAttachFile (ApexPages.StandardController controller) {
oppty = (Opportunity)controller.getRecord();
uploadedList = new List<String>();
}

public void attachFileAction() {
Attachment a = new Attachment();
a.ParentId = oppty.Id;
a.Name = fileName;
//NOTE: Here, I am commenting out segments of the code just to see if the error would go away, but it does not help.
//a.Body = fileBody;
//insert a;

//Clearing out the contents to avoid hitting viewstate limits
a = null;
}

public PageReference doneAction() {
return new PageReference('/' + oppty.Id);
}
}