I'm not sure how old this model is, but if it carries the Yamaha badge, it likely is of pretty solid quality.http://www.yamaha.com/yec/products/productdetail.html?CNTID=200506&CTID=5000300&RLTID=1504&DETYP=RELATION
HDMI is not incredibly important, but if I was looking to do a serious 5.1/7.1 home setup, I would only buy a receiver these days with it, and likely with HDMI 1.3 compatibility.
Yet, not having it is just going to keep you from enjoy uncompressed HD audio from a device (like Blu-ray) which doesn't have 7.1 audio outputs and internal HD audio processing. Yet, you can still deliver HD video via component, or by HDMI directly to your display and use digital audio via coaxial or optical to the receiver.
I would consider how much you spent on it as it carries as much of a warranty as any online purchase, etc. so you should not have paid more than $300 for the receiver for sure... Hopefully less.
At $250 or so, it's a pretty solid deal on a decent receiver.
- Theater, whole house audio, and technology consultation during the build and installation process in the Washington, DC metropolitan area.