What is UPconverting?

looking at Onkyo 605 vs 705 and one attraction is the 705 upconverts...whatever that is. the 605 will convert any imput into it's single HDMI output. Is that good enough?
In general "Upconverting" "UpSampling" or "Upscaling" is a process that mathematically matches the pixel count of the output of a standard or non-hi-def signal (such as standard DVD) to the physical pixel count on an HDTV, which is typically 1280x720 (720p) or 1920x1080 (1080i). So it gives you a better picture, some players are better than others as some tend to soften picture in the process. Please dont get confused and think this will give you Hi-Def quality f a HDDVD or BluRay player...but it can be much better.
"Upconverting to HDMI" as it relates to the Onkyos means you can connect any type of video source (analog or digital) and the receiver will perform switching and "upconvert" any signal to HDMI output. This allows you to connect VCR (analog composite video), DVD, Cable/satellite TV (analog component video or HDMI digital video) or any other video source to the receiver, but only connect one HDMI cable between the receiver and TV.

I went to the Onkyo site to compare the differences and unfortunately I could not determine if there is any difference between the 605 and 705 regarding "upconverting to HDMI". They both are listed as having the feature, but the 705 verbiage clearly defines it's abilities, while the 605's verbiage is less clear.

I would ask the question on the AVSforum. There are lots of Onkyo 605 and 705 owners that post there. BTW, I own the Onkyo 703 and I'm a big fan of the brand after having owned lots of other brands.