In the last couple of months I finally upgraded my Dell XPS M1330 from 2 GB to 4 GB and what a difference it makes! Yes, since I am running 32 bit Vista my machine only sees about 3.5 gig of the total 4 gig. With 4 GB of memory (and a 4 GB SDHC card for ReadyBoost) I see a remarkable improvement when using my Virtual Machines on the 1330.
Now that I actually have enough RAM to run my Vista host system (~1.5GB) and a SharePoint VPC (2GB) I find that I spend more time designing from the host than I do on the VPC. I slide in a host file entry so I can hit the VPC from my host when not connected to a network. Then I use SharePoint Designer a lot which allows me to design from the host against the VPC. That might surprise a lot of you who know me. I rarely used FrontPage 2003 with SPS last time around. I try to keep my host machine generally clean - no Visual Studio ect, only Office and some files. I do install on my host machine SharePoint Designer which allows me to remotely connect to my VPC. By using the host system as a client to the SharePoint VPC I get to spread the load across the host and VPC resources providing me a much more responsive VPC and design experience. I also keep a copy of BDCMetaMan and SQL Server 2005 Tools on the client which allows me to connect to a VPC instance like SPD.
I still jump on and off the VPC for key development but most design and configuration can take place from the host. Overall using the host as a client and the VPC as a server has increased my productivity.