The cheap system I put together to use at work (to replace a 1.8 single processor G5 w/ 1256MB of DDR400) runs CS5 very well. In those cases, more RAM and/or a GPU that CS will use for acceleration are more important. Generally your processor and HD are going to be bigger factors on performance in CS, other than some of the more optimized apps like Ps, AE or Premiere. That being said - if you've got the money, it's worth paying the small amount now to get 8GB instead of 4GB with RAM prices as cheap as they are.

Regarding the display options in InD and setting it to use High Quality.IME that hasn't been a factor on RAM use either. I'm surprised Illustrator doesn't let you do it, actually. Ps is really one of the only CS apps that does this (I believe After Effects is another one). I don't think I've ever seen it go above 2GB, maybe 3GB at most (and I really don't recall it ever being that high).ДЄs stated earlier.InD is not like Ps there are no options to allow InD to use more RAM or to be able to adjust how much it's allocated. I work with large spreads quite often.sometimes 5k pages with a high res TIF or PSD linked image on the master page, along with auto page numbering. I rarely ever see InD use more than 2GB of ram, and that's with files with either a) a lot of pages, b) a lot of high res links, or both.

Adobe indesign cs5 page numbering