Since Gregg's throwing down in the comments section of the last post: I've read so many management books I can find a management aphorism for any position I care to take. So, I could, for example, say that trying to save $500 per employee is an example of Jim Collins' "Rinsing The Cottage Cheese" from Good To Great.
But well, actually, as much as I like Jim Collins, I 99% agree with Gregg. $500 per employee is nearly immaterial; it's a fraction of a percent of your total budget, a fraction of a percent that will probably be earned back because the team is familiar with Microsoft, it's a known quantity, and it supports that one bullet point I need. The only reason OpenOffice is crossing my mind right now is because A) I use it at home - if it's good enough for the home why isn't it good enough for work? and B) bootstrapping mentality - we're starting a company, and therefore cash is like oxygen, and therefore if we can save $500 * x in those first few months without a reduction of our team's efficiency we're going to do it.
Speaking of lean thinking, at Treyarch we pirated a lot of the software we used to do game development. That's one way to think lean...but it's something I'm not proud of and wouldn't do again. That practice ended when we got bought by Activision - breaking the law is against Activision policy.
I don't think Greg's idea of keeping the schedule spreadsheet under source control will work - it's hard enough to get people to update their estimates and actuals every day - if when they try to do it they usually discover that the spreadsheet is locked by someone else it will never get done. And...one spreadsheet per person isn't quite an option, because even though tasks aren't fungible we do find that we're swapping them around from person to person enough for too many spreadsheets to quickly become annoying...
So I'm still in the Excel camp. Although if Joel Spolsky releases a version of FogBugz that has his scheduling system built in I'd spend the money on that instead.