I have a ctx 550 projector that I can't switch from video to computer. Is there an easy solution?

Hey, I just recently started looking into projectors, and came across this site. Definetly the best resource for information on projectors I've come across. Anyways, I do have a few basic questions about projectors. The ones I've been looking at are older out of production CTX LCD projectors. I'm on a very limited budget, and my needs and expectations are not particularly high, and these seem to fit what I was looking for. I'll be able to get one for less than $250. Anyways, if anyone can help with a few basic questions it is much appreciated.. For starters, are there any particular things I should know about projectors that aren't obvious? I guess that is incredibly vague, but hey. I mean the sort of things that if I don't know, I'll turn my projector into a paperweight. Second, do any projectors experience lag like some HDTVs do when using a standard definition source? This is a concern for me as I'll be using mine some of the time for gaming. Edit: Because I realized I was wrong about this.. Also, does anything need to be regularly replaced on projectors aside from the bulb? Finally, can anyone here who has experience with CTX EzPro projectors in the 500-700 range tell me a bit about them? The reviews on here are good, but I'd like to read a bit more. I am also aware of the dust issue on some of these models, and that is not a major concern (my use will be light - maybe 10-20 hours a week), so don't worry about that. I will be using it in a basement which has no ambient light (unless I turn on a lamp) projected to about 85" on a type of bathroom sheeting stuff you can buy at hardware stores. I don't really need great quality, just not completely horrid, and I don't need HD, advanced inputs, etc - I'll get a better projector (likely DLP) when I'm through with college in another year and a half. I guess I have quite a bit of information I'm asking for, but any little bit helps. Thanks a lot!