Yes the SR5 has an option to record in MPEG2 SD or AVCHD HD.
What I was saying about comparing the SR190/200 and the SR5, is that if you are only interested in SD, there is no real advantage to the SR5.
But...
To your question
untill I have one to tape in SD....
You aren't stupid

, but I wouldn't do it like that. The reason being - you want what you shoot today in the highest quality possible. If you shoot in HD today, then eventually when you get the kit to play it, you can reissue your old footage in HD. If you shoot SD now, you are stuck with SD.
I have a HD cam (HC1).... I don't have a HD-DVD player or anything like that, and I don't even have a HD TV. But I still shoot in HD. I create a SD DVD, and a HD master (in my case on HDV tape) to save for later. Eventually I'll get a HD TV and DVD player, and can reissue my old master. In the meantime even on a SD display my footage looks very good.
So if you went for a SR5, I'd suggest to shoot in AVCHD, convert in software, and save that AVCHD footage. In the very short term (e.g. if you don't have the software yet) you can shoot SD... but I'd start shooting HD as soon as you can.