I run my VJ-1204 with Wasatch Softrip. It's on a dual P4 Dell with 4GB ram.
As for sitting idle, most everyone will tell you the best advice is don't if you can help it. That said, I turn my printer off every night and leave it off all weekend. Other than a quick clean the next morning it gets right back to work with no issues. Longest I've left my printer off was 4 days during Thanksgiving and Xmas holiday.
*I run only Mutoh brand ink and you must take into account the current condition of your head, dampers, capping station, pump, etc. If you have a weak link somewhere in there, you'll have problems.