I know they are UMTS country. Can I rent 3g modem for a week?
There are 3 cell phone providers in Egypt:
Each one of them provide wireless data connection. There are two types:
1- USB modem, which is the easiest way:
Normally etisalat is the cheapest one.
The problem with this USB modem, is that you have to buy the USB modem (cheapest USB modem is 99LE (~17$).
You will have to buy some plan (e.x with etisalat, you pay 19LE to get 110MB with high speed internet, after 110MB ends, you will be degraded to 64Kbps, which is awfully slow). You can re-pay another 19LE and get another 110MB with high speed.
2- The other option is cell phone internet. You get cell phone data plan, and use tethering in you smart phone to give internet to your laptop. You can use the per/day plans, you buy credit with 3LE, which gives you about 15. You can go with this if your usage is REALLY light (twitter, facebook status, ...).
Egypt uses GSM phones, on the 900 and 1800 Mhz bands, and have freed up 2100 Mhz for 3G usage.
Vodafone Egypt has what they call 'USB Modems' which would be what you're after, and their data plans page would seem to indicate various prepay and postpaid options. But you're probably better off just chatting to them when you get there to decide on your best option.