The final version of Vista SP1 focuses on under-the-hood improvements to reliability, security, and performance, with very few changes made to the interface or Vista's features.
You'll find occasional cosmetic changes here and there in SP1. For example, BitLocker encryption lets you choose which drives to encrypt. In addition, the Disk Defragmenter (Control Panel --> System & Maintenance --> Defragment your hard drive) now lets you choose which volumes to defragment.
Aside from these, though, most changes are under the hood. Microsoft touts a variety of performance, security, and stability improvements as well as other plumbing changes.
For example, SP1 supports the ExFAT format, a new format for flash-based devices that supports larger files and more files per directory than is currently possible. Microsoft also claims that SP1 is more stable than non-SP1 Vista, and reduces system crashes. It also says that SP1 is more secure.
For a look at some more changes that SP1 makes, you can check out Vista SP1 FAQs.
Windows Vista SP1: Specs
- 800MHz processor
- 512MB system memory
- DirectX 9.0-compatible graphics processor