It’s been a while since I’ve created any broadcast graphics in Photoshop, so I can’t give you the specific details. However, the thing that you’ll need to do is to create your Photoshop graphics in an NTSC-safe manner. NTSC has a few differences over DVD/HD that affect hoe the graphis are displayed.
In general, NTSC has: a limited color space that causes certain colors to look fuzzy, a limited amount of resolution that makes lines look fuzzy/distorted if to narrow, less overall resolution than DVD/HD, so you los detail, it is also interlaced which means that the picture is drawn in 2 passes instead of 1 and it draws every other line in the scans – even first then odd, and some more stuff that I’ve probably forgotten about.
I’m sure there are some tutorials on Creative Cow that show how to make the best graphics for broadcast & DVD/HD. Well, since we’re now broadcasting HD, I guess that’s not quite accurate, but look for some older tutorials or google Photoshop+NTSC. Once you get them good for NTSC, they should also be okay on DVD/HD.