Firstly I'm trying to find out if you can do an HttpRequest using Salesforce sites my code is:

        Http h = new Http();
        HttpRequest req = new HttpRequest();
    	req.setEndpoint('http://website.net/test.php?e=teststs');
    	req.setMethod('GET');
    	h.send(req);

 But I keep getting "Authorisation Required" appearing... do I need to set some other permissions?

Also is there a list of things you can't do with Salesforce Sites?

Thanks

Francis

I am exceeding API request Limit, I am using Salesforce Professional Edition and updating records in it from a .Net Application. 

.Net application updates multiple object at a time (Accounts, Contacts, Opportunity, Cases) 

I have tried to make my .net code efficient , but still I am exceeding limit, and than I have to wait 24 hours until it releases the limit. Is there any way to Increase API limit or any other way?