Vmware server is meant to run mostly in the background, with a web interface for you to control the VMs.
From there you can open a remote console through a browser plugin, which is capable of doing most things you'd need it to. (Although it strangely lacks a ctrl-alt-del button) There is no hardware acceleration support in server.
Workstation runs in usermode, so you start it after logging in. It runs as an application rather than a service. It also supports multiple snapshots, if you need to rollback changes often. Server only allows one snapshot per host.
Personally, I have a WinXP VM in VirtualBox that I've been using for development for the past year. VBox supports seamless mode in Linux, which was the primary reason I chose it over VMWare. I believe VMWare Fusion does the other way around, seamless mode for Linux or Windows on a Mac host, but they don't support this on a Linux or Windows host to my knowledge.
It has worked well so far, just one caveat: back up your virtual disk! Especially if you're going to play around with snapshots. And setup a source control system outside of the virtual environment so you can get at the code if the virtual disk is inaccessible.