Memorex isn't great, but you gotta work with what's on hand in a clinch. As long as your 3576 doesn't appear to struggle with it, and discs burn to completion and finalize without a hiccup, you should be OK.
Blank DVD media might as well be voodoo for all its unpredictability. Statistically, Memorex, Ritek, Maxell, TDK and the various CMC spinoffs have been prone to burn issues that aren't noticed immediately but cause playback degradation later. But they don't ALL degrade, or the companies would have been sued out of existence by now. Just a certain percentage degrade, depending on initial burn quality and other factors.
You're playing the odds a bit. If the videos you need to get off your 3576 are just typical TV shows, it isn't life-or-death: you just want the DVDs to last long enough for you to catch up with your viewing. If you want them to last beyond that and keep them indefinitely, you could consider duping them onto better-grade Verbatim or TY 8x or 16x using your PC (later, when you can afford to replenish your stock of good media). It never hurts to have a backup copy of important discs.