Vista itself is not a resource hog but a newer version that is intended for the much newer hardwares seen now then when XP first came out. The requirements are higher on memory like XP is over previous versions like 98.
People that haven't been running their own systems too long and have not worked with the older versions are generally unaware of the large changes seen across the board not just with only the new version. I went right after Vista here when it first came out in order to more or less take notes on how different it would be.
More stable in many ways over XP, improved crash control when a game or app locks, a small increase of ram needed as expected since 98 was 16mb compared to XP's recommended 128mb minimum to Vista's 512mb. It's incremental compared to now seeing memory capacities like 8gb, 16gb, and even just being seen now 32gb for a desktop board.