Giant Rincon vs Mongoose Rockadile

Hi,

I live in India and the choice of good mountain bikes is extremely limited here. After a loot of looking around I managed to find two people selling
1) A Mongoose Rockadile 2004 model (Second hand in good condition though)
2) Giant Rinconn (Brand new, but double the price of the rockadile, and quite a bit above my budget)

Ok, before I go on here is how I intend to use this bike...
1) I am 82Kgs/180lb, 6ft(182cm)
2) I plan to use it 3-4 times a week to ride inside the city for about 10-15km a day. This is the max. I don't see my usage going higher than this.
3) I like to ride my bikes fast (as fast as my legs can take me) and rough
4) Although I will be riding only inside the city, the city roads are spotted with pot holes (some 0.5ft deep), some roads barely have any tar left on them and some roads have been completely washed away by the recent rains here.
I can try and avoid the pot holes but then I see myself going straight over these pot holes quite often than not.
Will these bikes manage to take such a beating over a period of time.

Next.
What sort of maintainance do on these bikes in general? I'm sorry if this is a very basic question, but I have never really owned a bike for all that long. All I know is that when I did have a bike, I really enjoyed cycling a lot.

I would like these bikes to last me atleast 1-2 years, before I make any major replacements like changing the tyres/chains/gears or atleast 2 years before I have to change things like the forks. Is this a reasonable requirement given my usage specs?

Any help will be greatly apreciated.

Thanks,

- Sid