
Should've known this was coming. Lets' see how far we can get. I'll push the open source alternative if available (iLife isn't free, for example).
Time Machine: Check
lifehacker.com for backup utilities that come close (even they admit that Time Machine is point and click easy).
Spaces: Virtual Desktop Manager or
VirtuaWin
Command Line/AppleScript: Cygwin for bash, or
PowerShell for AppleScript-type coding (standard in W7, available for Vista/XP).
LittleSnitch: What you are looking for is a software/personal firewall. Something like ZoneAlarm Free for your parents' machines, as it's user-friendly, if a little resource heavy, or Komodo Firewall Pro.
Automator: AutoIt
Smart Folders: That's a good one. Windows 7 has Libraries, but I'm in no position to compare the two.
File System: It's Unix. No comparison there.
Front Row: Windows Media Center for one - Vista and W7 versions are very good. There are
other media centers out there if you don't want to use that one though.
iLife: Let's split these up, shall we?
There's
iPhoto - use something simple, like
Picasa (excellent organisation capabilities) - or
choose for yourself.
Then there's
iMovie - we can take a look at the plethora of Movie-creation software available for Windows - or we can simply turn to
Microsoft's own Movie Maker 2 (now
renamed and updated).
Next is
GarageBand - may I direct you to the
tons of sound editors out there, while drawing your attention to
Audacity - also available for MacOS X.
(I don't believe the rest of iLife is worth the effort...

)
Remote as standard: buddy of mine picked up an LG laptop with remote as standard. It depends what you buy.
K, so I didn't say it would be a smooth interface - but I did say I could pretty much duplicate the software. Some of the replacements are better, some not - but they're there.
I have nothing further, your Honour.