Remote Desktop from Windows itself?
It works better than anything else, its much faster too. Forward a port on your router and you can use it from the internet. Port forwarding allows you to forward something like 22 to 3389.
I would strongly urge you to
not port-forward Windows Remote Desktop connections (or VNC either). Windows does not SALT their passwords, and I just would not trust it at all to not have all sorts of buffer overflow problems. VNC doesn't even try (because they know it is a bad idea, I think, and because you
can tunnel them through SSH), and their passwords are limited to 8 significant characters and transmitted in the clear.
Like I said... Make a VPN. If you have a decent router, you can probably get dd-wrt to run on it and use that (or something similar). That lets you access everything on the network too - file shares, printers, etc. It'll be slow, but it works. And you can do other things that will perform well, like run a FTP server at home for easier/better performing remote file access, and not have to worry about obsessively patching the server every other Tuesday. Fewer points of failure=better.
If you don't have a decent router, get one. Get a crappy old PC off of eBay or something, stuff a couple network cards in it (buy Intel ones and save yourself a headache) and throw the free home license to Sophos UTM (formerly Astaro) or pfSense on it. Use your existing router as a dumb switch (turn off all the DHCP stuff and don't use/plug-in the WAN port, just use the LAN ones), or buy a cheap one.
VNC just plainly sucks if you ask me. Input lag, slow screen updates. It's killing me when I have to use it.
VNC isn't great over WAN, particularly if the server's uplink is slow. It can be very good if the server has good upstream bandwidth. The problem is, most of us in North America have piss-poor upstream bandwidth.
I use VNC almost every day to access my machine at the office and it SCREAMS. It doesn't feel native, but it is
completely usable. Of course, my office has a dual, symmetric 20gbps connection to the Internet. My client-side upstream doesn't matter much (it is just sending easily-compressed "control messages" to the server), and I usually have decent downstream connectivity (except on hotel wifi where everything is miserable). But the server machine in this case has essentially-unlimited upstream bandwidth, and this matters a lot (because it is essentially sending a big HD video stream to you).
Connecting to my machine at work with VNC using my iPad on 3G even works decently well.
Inside the LAN, VNC can perform pretty
darn well, if you get the right server and configure it correctly (with a good mirror driver and whatnot). TightVNC and UltraVNC are the two best for Windows. They have different strengths.
Still, though... I think I
agree with InflatableMouse here, especially in your situation.
I use Windows Remote Desktop to connect to a bunch of my VM Servers at the office, and it works equally well remotely and on-campus, performance-wise, and the clients are definitely a lot less twitchy. No matter what I do, TightVNC seems to get periodically "stuck" and I have to manually refresh the client. Using UltraVNC as the server instead was much less prone to this, but they don't handle dual-displays well, and almost every machine I have/use has dual displays. Windows Remote Desktop is annoying in its own ways (it is annoying to manage lots of different computers without some of their higher-end tools, and their Mac client is much crappier than the Windows one.) But, it is also easier to set up to run as a service (so it is running even at the login screen) and the system just "knows" a lot more about how Windows works, and can re-use components much more easily without having to "stream video" anywhere near as much.
So, I don't know.... If you are just going Windows-to-Windows, I'd probably look at Windows Remote Desktop first. It is built-in, there is nothing to install and update separately and debug, and it works very, very well. You're almost certainly going to want that "server" to run Windows 7 though. Might even need to... I'm really not sure of the state of Remote Desktop support on XP. And, Power Shell is Windows 7, and all the management console stuff will probably work better too. And there are plenty of iPad apps if you need that. They're just not as nice as the VNC ones, IMHO.
The killer VNC feature for me, though, is certainly the cross platform support. I have one place to go for all of my remote machines, whether they're Linux VMs, a Windows box, or one of my Macs. And I can use any of those platforms as clients too. If you don't have that concern, I'd look at Remote Desktop.
But don't open those ports.