If your PC can run Vista Home Premium, it can run Windows 7.
I would have suggested downloading and trying the Release Candidate, but that is no longer readily available. (It's still legal to install, but it's not available for public download.) There's a 90 day evaluation version of Windows 7 Enterprise that is available for download by IT professionals. (How does MS know that you're an IT professional? You tell them. Honor system.)
I can't begin to guess whether you'd find it to be a worthwhile upgrade. I presume that Vista runs OK for you. Windows 7 isn't radically different, and there are (in my opinion) no must-have features in Windows 7. I'm running pre-release versions of Windows 7 on my desktop and laptop. My laptop is a Compaq CQ50 105NR with 2GB of RAM. It's inferior to your HP model. Windows 7 runs well on it, perhaps slightly better than Vista Home Premium. (It's not a good machine for 3D games. That hasn't changed.) Clean installing Windows 7 allowed me to get rid of the last of the crapware HP had on it.
I like Windows 7, but it's not what I'd call transformative. I'll keep it because a) I'm a PC enthusiast and b) I got in on the pre-order price for the upgrade version ($50 Home Premium).
If you decide you want it, and have to pay the full price, I suggest getting it from a retailer (Staples, Best Buy, etc.) if you're in the US. Instant gratification. Otherwise, you can get it directly from Microsoft: Windows 7 - Buy and download from Microsoft Store
(disk, download, or both for an extra charge).
If you're a student (basically, have an email address with a .edu domain name), visit win741.com. Microsoft has a $30 deal for students.