The quad will.... Well, I don't know. This has always been an issue for me because scalers (doublers, quads, pixel for pixel devices) typically only manipulate NON-HD sources. That is, 480i material then output them at 480p, 960p, or something else.
I would expect that the scaler you are aquiring will not help with HD material.
But, I know for a fact that some DirecTV units have RGB output which you can hook directly up to your projector and get an awesome image. I mean really - the image is really about the best there is, and on a CRT projector it is even better.
Understand me on this: Despite the age of your projector, neither DLP or LCD is close to the same quality that CRT produces. CRT is still the yardstick by which all others are trying to be measured and if the projector is really good, then you may want to hang onto it for a lot longer... But, the lack of component input may prove to be very frustrating.
Do some research to find a component to HD converter - it may be $1,000 to own one though, but I expect they exist. If the projector rocks, then it may be worth it to get the converter instead of a new projector...
I just took a quick look through my Extron catalog and I found this:
http://www.extron.com/product/product.asp?id=cvc200
Which has an MSRP of $895.00 so can probably be had for under 800 bucks.
What do I like best of HD cable, DirecTV, Voom... Don't forget Dish!
I use HD cable (cox), I think Voom and DirecTV likely have higher quality but, there is a major investment going on when you talk about DirecTV and Voom due to the requirement to purchase a lot of hardware and install sat dishes in your home. HD cable is a much less expensive way to go to start off with and you will likely get your cable modem as well so you may get a 'package' discount on things. If you switch entirely to DirecTV then you have no need for cable, and you will pay more for a cable modem hookup if that is what you use. In my opinion, DirecTV is better, but ends up costing more. So, it is a money issue. If you are in a solid financial situation and are prepared to spend a little more for more quality, then go DirecTV... If you are a little more price concious and are willing to lose a little quality, then go cable.
Voom looks like it has a GREAT promotion running right now that may be worth getting in addition to cable or DirecTV. But, it will not replace cable or DirecTV because of a lack of channels.
I haven't looked at DirecTV in a while, but you may want to check on the status of local stations in HD over DirecTV as this can make a difference. I like that with Cox I get ABC, CBS, NBC, and Fox from my local Washington DC broadcasts which include the Skins games on Sunday in HD on Fox. That combines with the internal DVR function of the box to provide some nice viewing experiences.
But, DirecTV can give you a lot of that stuff - it just costs more... and you get a little more quality.