yes get thermal paste, get the smallest size if you dont want to spend taht much its like $5-$18 for a 3g tube of arctic silver3 or artic ceramique, i'd recommend the ceramique
dont get a shim, unless you plan on moving your computer around a lot and you're nervous about your core chipping due to a heavy (copper) heatsink...
regardless of whether or not you buy the silent boost...
however, i admit i dont nkow if the tt silent boost comes with its own paste, and if it does, i dont know what it is, but buying a tube, allows you teh freedom to reseat your heatsink for a bunch of times (especially for amd cpus) without having to worry about running out of paste... also comes in handy for your northbridge, southbridge (for nf2 mobos), and vga chips if you later want tocool those better than stock