No worries, the Imperial Guard has AWESOME tanks! The Leman Russ is feared throughout the galaxy as its big gun is as destructive as any opponent can imagine (and there's lots of options for that big gun- each of them ridiculous!) and its thick armor makes the tank a real pain to have to kill. The IG also has great artillery tanks, between the good 'ol howitzer on tracks to the scary multiple rocket system (also on tracks). But best of all are the transports- the reliable Chimera.
The average soldier in the Imperial Guard is an adequately equipped human conscript who lacks the wargear and training to be of any real threat to the powerful enemies of mankind. Worse, this soldier is then stuck walking into a hail of firepower the enemy designed just to defeat the meagre defenses of that flak vest and pot-helmet issued by the IG. Both of these problems can be solved by loading a squad into the Chimaera and rolling right at the enemy. Not only is the soldier now safe from the deadly raking of bullets and bolts sent downrange by the enemy, but the APC has enough armor to survive small arms fire and packs enough firepower to make even renegade Space Marines take pause.
Let me be clear here. The armor is NOT thick enough to withstand heavy weapons or the more powerful assault weapons, nor are the vehicle-mounted guns powerful enough to kill a Space Marine easily or even scratch a heavy tank. But a Chimera IS protected enough to keep the soldiers inside a bit safer than if they were walking and it IS armed well enough to put out a large volume of medium strength firepower. This vehicle is so good, in fact, that a single infantry squad doubles in cost (or costs a bit more than simply double points) but triples in effectiveness. Why is 'Mech-guard' (and the very similar 'Leafblower', for that matter) so common in the tournament scene? THAT'S why!
My Blood Angels ALL have jump packs except the two Tactical Squads and a Death Company. But I have three Rhinos, so they can ride. My Ultramarines Battle Company is equipped with 5 drop pods, leaving three squads to travel the battlefield- in Rhinos. My Deathwing has three squads of deep-striking Terminator squads and three more who ride in, you guessed it, Land Raiders. My Eldar come equipped with Wave Serpents and Falcons, my Tau roll on foot except when I pay for their Devilfish(es)... hell, even my Word Bearers have three more Rhinos set aside for them! It appears that I can't live without a transport for any squad I own! Maybe it's because I grew up and live by the largest Army base in the world, mostly populated by the the US 1st Cavalry Division. Maybe it's because this philosophy of warfare has infiltrated my thinking and now I use it in my 40k hobby. Or maybe it's just because I've always liked tanks.
In any case, let me ask the same question every Cav soldier asks every light Infantryman-
Why walk when you can ride?!?