*Should I get a laptop in Poland or in the States? I'm considering a Mac or an HP laptop. I haven't decided which yet.
go for HP (actually go for some Chinese make - like Asus or Acer or maybe Lenovo - I guess they are cheaper and actually HP is on the same level of serviceability as MAC in Poland) (if it's gonna be Windows or Linux powered) - there is very little in terms of Mac presence in Poland which will definitely be reflected in the cost and availability of service in case anything happens
cell phone is easy if you just need it to talk - or just surf occasionally (you need to have a set with a built in modem or by a modem unit for your laptop) - you just go to any shop that sells phones - you can then buy a pre-paid card in a newsagents ('kiosk') - this is also where you top up - if you have an American handset check if it works with the European GSM (frequency mismatch - most new phones sold here in Europe are said to be designed to operate both in Europe and the US but have no idea if it's the same on your side of the pond)
as for internet - I guess you wouldn't settle for a GPRS speeds of transfer so you need a contract - in order to have a contract you have to be established here - have a residency etc (e.g. some papers to confirm that you live here legally, have and adress etc) , then you can apply for a contract with either cable internet companies (main telecom companies (Telekomunikacja Polska, Netia, Dialog) or cable TV networks) or if in a bigger city a GSM (or rather its younger brother LPT) internet providers (LPT is provided by Polsat only, lower speed GSM internet is provided by the main cellular operators (Orange, Plus GSM, TMobile) - the GSM in the cities can have some 500 kbps transfers (at least they say so - I am not completely up to date with that information cause I don't live in a city an such things as EDGE, HSDC are not present where I live) - the cable telecoms and cable TV networks in the cities provide very high speed transfer internet including fiber optic connections (but the latter must be quite costly) - an avarage internet contract will set you back some 40-60 PLN (our currency)
EDIT: a 25 Megabit internet is not your average internet in Poland (more like 4 Mbit)