mvc3 - using partial views in a different area

I'm not sure if you mean Html helpers, or razor helpers when you say "helpers" In any case, I only create Html helpers when it's a small, idividual item like a control.

If you mean Razor helpers, then they are different from Partials in that you can call them like functions, passing whatever parameters you want. Partials are largely stuck with the "model" system (and of course Temp/ViewData/Bag.

It's all about how you want to work with the code.

As for your Partial. You have to include the suffix.

@Html.Partial("~/Views/ControllerName/_PartialView.cshtml", Model)

Since the questioner asked about areas here's how to do it in an area

 @Html.Partial("~/Areas/Store/Views/Pages/Checkout.cshtml")