I do suggest you call Dish, and inquire about the Whole Home Upgrade (WHUP) promotion, to get your setup from SD to HD, assuming of course that your receiver is leased.
They'd most likely send you a technician that'd charge you $15 (assuming you have Service Plan on your acct), the technician would replace your old DP500 with a new DPP1000.4, and your SD receiver with a new ViP622 or ViP722k, enabling your setup to be HD ready.
But if you want the best deal, I suggest you enroll in autopay and paperless billing so that you'd be eligible for the HD Free For Life promo, so you wouldn't have to pay $10 every month, or the $99 one-time HD Free For Life fee. That way, you save more.
I also do suggest you get Service Plan. It's like an insurance plan for your equipment, just in case you'd need a technician visit or replacements to your equipment, for discounts galore (pay just $15 for a technician visit rather than the usual $95 if you don't have the service plan) and free shipping for equipment exchanges, for just $6 monthly.
But then again, yeah, that's just my two cents. Call for the WHUP already, have a visit scheduled. Don't do it yourself.