Top 10 in general?
1. MSE (Defender on 8)
2. Malwarebytes Live (goes on sale for $15 all the time) & CCleaner
3. Tinywall (for Vista or newer - if needed on XP, I use either Comodo or Zonealarm)
4. Chrome & Java
5. 7zip
6. VLC
7. Picasa
8. Imgburn
9. Adobe Reader & CutePDF
10. Snagit (v11 does basic video recording, too)
If it's Windows 8, I always use StartMenu8 to add the classic Start Menu back. If it's Windows XP, I always install Taskbar Shuffle (lets you move taskbar window buttons around like Windows 7). I use Pismo File Mount for mounting ISO files as folders (although a couple programs need to be mounted in a virtual CD drive, so I use SlySoft's free Virtual CloneDrive for that). If they want extra photo stuff, I use Irfanview for viewing & Paint.NET for a Photoshop/GIMP alternative.
I also usually toss on Everything search, since a lot of times it's easier just to pop something open by filename or extension. On Windows 7, for network searches, I use UltraFileSearch. For remote access, TeamViewer. Microsoft Office is pretty standard; I've installed LibreOffice from time to time (the new OpenOffice), but generally if someone doesn't want to shell out for the official Office software, I just tell them to use Google Docs.
If they're into downloading embedded videos, like on Youtube, I install Firefox with the Video DownloadHelper program, which I've found to be super-convenient. For ripping movies, usually a combination of MakeMKV, Handbrake, DVD Decrypter, DVD Shrink, RipIt4Me, and Plex. For emulator gaming, Hyperspin. For virtualization, either VMware Player or VMware Workstation. For hardware testing, the usual Aja System Test, Prime95, CINEBENCH, and Memtest86+ (on a CD or USB key though).
For backup & drive management, EaseUS Partition Master (resizing disks), HDTune (check SMART Status & do speed tests), Active@ Undelete (file recovery), Genie9 Timeline (Windows equivalent to Apple's great Time Machine continuous backup software), and Macrium Reflect (one-time & incremental disk images & disk-to-disk cloning). I do love Snagit for screenshot capture & annotation (especially for arrows & boxes), but Greenshot is pretty close if you need something free. A lot of my users like DisplayFusion (dual-monitor wallpapers & puts the taskbar on both TV).
One big one I use is Macro Express, which is my favorite Windows automation tool. So many uses. I also really like KeyNote NF, which is sort of a nested Notepad replacement. Kind of like Evernote, but more direct. Evernote & Dropbox are also great, plus Google Drive on the desktop. Launchy is pretty useful if you like doing hotkey searches & launches from your keyboard. If I'm digging into something, the usual stuff like Resource Hacker, Belarc Advisor, AutoIT/AutoHotKey/Sikuli, Process Explorer, PowerShell, FileASSASSIN, and InstallWatch work great.
