Kaspersky is nice as well, but has become a bit bloated, and the way it uses NTFS streams and rootkit-like method for hiding those streams is a bit icky (see sysinternals' rootkit revealer forums).The new KAV/KIS version 6 does not use NTFS streams anymore (and so no rootkit method for hiding them). Has low memory usage and various options to optimize the scan (eg. only scan new and changed files), as well as an option to concede resources (ie. CPU) to other apps during a scan which keeps the system running smoothly. It is truly modular, in that you only have to install the modules you actually want.
NOD32 uses more memory but is lighter on CPU.
Big problem with NOD32: it doesn't cache file status, so every time you boot your system, files have to be re-scanned, which makes first-launch of apps pretty slow (AMD64x2 4400+ here, and it *is* noticable >_<). Also, I haven't found a way to disable the background/instant file scanning that persists through reboots.I'm sure there is an option to only scan new and changed files in NOD.
XMinus1 - It seems odd that you mention bloatware with regard to AV's, but yet use SpySweeper. From my experience, SpySweeper used massive amounts of memory (upwards of 40MB-50MB).