The analysis and reviews of Vista are starting to come in - especially with respect to one of my favorite features - Superfetch. I blogged a bit about this in the past (about how Superfetch will proactively fetch applications into memory based on usage patterns so that they are already paged in from disk before you need them) but I have some real world experience with Vista on a variety of memory configurations and processors now and I'll offer my own real world experiences.
1. Vista on 512MB of RAM - I wouldn't go there - at least not without a USB 2.0 memory stick of at least 1GB in size capable of using ReadyBoost. Superfetch and all of the new services and 'stuff' that runs by default in Vista just make this a painful configuration . . . you'll find that pretty much all of your 'avaialable' memory is being used just by Vista in this configuration - leaving precious little for your apps. You'll see the hard drive paging all the time although ReadyBoost can mitigate this somewhat.
2. Vista on 1GB of RAM . . . this is my own personal 'minimal acceptable' configuration for Vista. At 1GB of RAM Superfetch is having a good time and you will definitely notice a dramatic speed up over 512MB of RAM. You won't need to use a USBFD with ReadyBoost but I'd still recommend it. I ran Vista with 1GB of RAM for almost a year and I would go a week with my 2GB ReadyBoost USBFD and a week without it and I could definitely tell a difference every now and then . . . some things would just load stupid-fast when the USBFD was inserted (like Acrobat, Media Player, IE).
3. Vista on 2GB of RAM . . . this is the 'sweet spot' for Vista IMHO. At 2GB of RAM Superfetch is happy AND you have enough RAM left over to let most / all of your applications run without needing to hit the swap file all the time. I've been running 2GB of RAM on my new notebook for a couple of weeks now and haven't really even bothered to insert my USBFD and attempt ReadyBoost. I just don't see how the OS can possibly go any faster. 🙂 It's freaking stupid-fast as it is and the hard drive barely is used . . . I may get an Apacer Steno (the USBFD that much of the Superfetch devs use) since it's fast or a Patriot Xporter (or whatever its called - which is also very fast) and give ReadyBoost a whirl - but much fo the reviews I've read so far have indicated that you won't really see any gains with this much RAM. I have used XP for many many years and with Vista and 2GB of RAM, I have never seen applications load this fast . . . it's damned near instant for just about everything I use on a daily basis.
Which brings me to my final point - upgrading. 🙂 If you plan to run Vista (and you should for no other reason than improved security and less downtime) - I strongly encourage you to upgrade your memory to no less than 1GB and to 2GB if you possibly can . . it's not nearly as expensive as you might think!
I bought my wife a notebook about a year ago - it's an AMD Sempron 3200+ thinger and it only had 512MB of RAM with a huge, huge screen . . . we paid like $799 for it . . . I knew when I bought it this was a 'borderline' Vista-proof machine but I knew she'd be running XP on it for a long time and I knew memory prices would continue to fall. I was very pleased this weekend when I ordered 2x 1GB PC3200 SODIMM's for her notebook and it only cost me $150 total. $150 for 2GB of *notebook* RAM . . . that's just insane. I love NewEgg . . . they arrived last night, and I installed them in less than 5 minutes. She's getting Vista x64 and Office 2007 tonight and I'm confident that she will love Vista with 2GB of RAM. This small RAM upgrade has extended the life of this notebook many years . . .