First boot took ~10 seconds because it had NOTHING loaded. It has gone up because it has to compile the background files together so that you programs that start when windows boots come up with it. That and the updates mixed will slow it down a little. Nice thing about windows 7 is it likes to use resources to have base files ran in the background so they pop up faster once you click on them. This pulls on the system, along with every update you add and if you have alot installed and auto-starting with windows can really pull load times.
Mine takes about a min to come up with a 3.4quad, 4GB ddr3 1600 ram (about to jump to 8 or 16gb depending), and a sata 6.0Gb/s WD 640Gb drive. When I first setup the system it was like ~10-15 sec but it has slowed over the years and take a min or so, but once its up it ready to go and fast as ****.
I wouldn't worry about it too much, now it takes like 5 mins, or runs slow once its loaded, or starts having errors then you likely have a list of problems that need to be addressed.