This is not a priority order, but just a collection of 10 favorite utils.
1. Everything – An ultimate ntfs drive search utility. Takes less than a minute to scan (first time/any time) a 1tb drive! Wish for its linux version as well.
2. CCleaner – Great app to clean up the desktop, registries, and unwanted waste. Also uninstalls programs the easier way and much more. The other products from piriform – defraggler, recuva are also very useful.
3. Microsoft Security Essentials – Windows has been doing a great job especially since the last year. I love this nifty little antivirus/anti-spyware program.
5. PDFCreator – One of the best PDF Creation tools. I used to use CutePDF Writer which creates a pdf printer on your machine and a simple print operation generates pdf. PDFCreator does the same and more brilliantly. It even creates a single pdf from multiple files – just select all, right-click and print. Awesome!
6. Q-Dir – There are a lot of explorer replacements. But this one is one of the simplest multi-pane utility I have seen.
7. Executor – Another gem. If you have ever used a launcher (launchy, gnome-do…), you will love this. Way more flexible and way less resource-hogger. Includes file-indexing, custom urls, hotkeys and what-nots.
8. Geany – The best replacement for Notepad. I like it more than Notepad++ or any other utility out there.
10. foobar2000 – If I listen to a song, its on foobar. It is crazy but I download foobar (if its not there) before listening to any song at a comp. Again in my linux wishlist (though I use it with wine).
Apart from these, Chrome/Opera browser (Chrome seems faster, Opera for bad net connections), 7-zip, VLC are also kind of a must for me. Partition Master, WinCDEmu, ReNamer are added bonuses.