Upgrade existing laptop, or replace?

I've got a Dell Inspiron 630m from about three years ago. It's been great, but it's starting to show its age. It came with a Pentium M 740 @ 1.73 GHz, 1 GB of DDR2 533, and a 100GB HDD. The hard-drive is almost full now, about 10 gigs of space left (after quite a few purges of old files/programs), boot times are getting long, and even basic multi-tasking is starting to stutter - as I loaded this Firefox browser my iTunes started skipping slightly. It's bearable, but in about six months to a year I know it won't be. Especially since I'd really like to set up a dual-boot with Ubuntu just to try out something other than Windows or my wife's Mac.

I think I could do one of two things. 1. Upgrade 2. Wait until this dies, and get a replacement.

I checked out my local Newegg (Canada) and I could probably double the RAM, and upgrade the harddrive to 320 GB for only about $170, w/taxes. It would solve my immediate problems, but the thing is, I have no idea how long it will be good for. Will my 533 FSB be limiting any gains I make? Would dumping that cash spare me a few more months, or years? What if I upgrade and then my battery dies, forcing me to get a replacement from Dell for a sizable sum?

I can't afford to buy a decent replacement right now, but in about a year I should have the cash. I'm just worried about my laptop (or even just the HD) frying and leaving me without anything (it's my only PC right now). If that happens I'd be forced to get a replacement, and it'd probably be a fairly crappy model I don't really want just to fit the budget. Which would suck.

Any advice on the feasibility of upgrading as opposed to just sitting and waiting for the best, would be appreciated.

I'd agree with frozenlead. Extra RAM never hurts and an upgraded hard disk certainly wouldn't hurt either I'd say if anything it'd be $170 well spent work it out over a year and it's less than $15. I'd say it's worth those $15 a month to get the upgrade and then you can sock away cash for a new machine in the new year 2010

I'd go with the 7200rpm it might take battery life down some but not something horrible like giving you less than an hour or some other major impact like that. As an added bonus it will help speed up loading times on apps