I've been searching for a computer myself. While I'm still a ways off from actually getting one I would recommend checking out the HP Pavilion P6130Y. In short it's pretty much a more modern update to the HP computers that came with Win XP Media Center 2005. Key features are:
-8 Gigs of RAM out of the box (expandable to a max of 16)
-750 GB hard drive
-AMD Phenom Quad Core processor
-A free upgrade from Vista Premium to Windows 7 if purchased before 1/31/10
It comes with Vista out of the box but you should be able to get the updrage to 7 once that's on on October 22nd. As a matter of fact that free upgrade should be on almost any new computer you buy before that date provided it originally had Vista. Depending on the store and the make of the computer you may either get an upgrade disc or a product key for a download. As for the paticular computer I've suggested I don't quite know how that compares to the specs on your current one. However all in all it should be a fairly good choice for nearly anyone. It comes with a quad core processor and 8 gigs of RAM out of the box. In laymans terms memory should be far from an issue. I'd imagine it'd have Microsoft Word as well. It's very rare that I see a computer without it. The only real issue I see with this paticular HP is the fact that it's got an intergrated graphics chip. Provided you aren't looking to play WoW, Aion, Fallout 3, ect that really shouldn't be an issue either. The old A1130N that I use to share with Brandy/Asi when we were still living together had a Radeon X200 as it's intergrated chip. Now I have no clue about the programs you use but here's a quick rundown of what ran ok on that chip and what I had problems with. It ran WoW fairly decently outside of major cities. My average framerate was about 25 FPS on high graphic settings (it wouldn't let me pick ultra on that chip). 25 FPS isn't exactly great but it's also not bad. Most older games (such as Morrowind) ran wonderfully on it. Games such as Oblivion however had serious slowdown issues on even the lowest settings. Video on various websites such as Hulu and You Tube was also fairly smooth. I also occassionally used things like Windows Movie Maker quite a bit. Personally I don't know if that chip was capable of running the desktop in an HD resolution due to the fact that the monitor that was hooked up to it was a plug and play standard res monitor. As a result the option wasn't there.
Now mind you we're talking about a computer from five years ago. I'm sure this newer model has better than an X200. I'm mainly just trying to give you an idea of how the intergrated chip ran to give you an idea of where you could potentially see problems pop up. This paticular model HP runs for about $629 at Best Buy but I have seen them sell it on special for $579 before. Overall I really can't see you going wrong on this one. The only real problem would of course be the intergrated graphics/video chip. Personally if I were you I'd spend an extra $60-100 to get a halfway decent video card to put into it especially if your looking to use an HD monitor with the computer.